diff --git a/django/contrib/gis/db/models/functions.py b/django/contrib/gis/db/models/functions.py
index 9d245b93c4..d24f16947f 100644
--- a/django/contrib/gis/db/models/functions.py
+++ b/django/contrib/gis/db/models/functions.py
@@ -16,12 +16,9 @@ NUMERIC_TYPES = (int, float, Decimal)
 
 class GeoFuncMixin:
     function = None
-    output_field_class = None
     geom_param_pos = (0,)
 
     def __init__(self, *expressions, **extra):
-        if 'output_field' not in extra and self.output_field_class:
-            extra['output_field'] = self.output_field_class()
         super().__init__(*expressions, **extra)
 
         # Ensure that value expressions are geometric.
@@ -137,13 +134,13 @@ class Area(OracleToleranceMixin, GeoFunc):
 
 
 class Azimuth(GeoFunc):
-    output_field_class = FloatField
+    output_field = FloatField()
     arity = 2
     geom_param_pos = (0, 1)
 
 
 class AsGeoJSON(GeoFunc):
-    output_field_class = TextField
+    output_field = TextField()
 
     def __init__(self, expression, bbox=False, crs=False, precision=8, **extra):
         expressions = [expression]
@@ -163,7 +160,7 @@ class AsGeoJSON(GeoFunc):
 
 class AsGML(GeoFunc):
     geom_param_pos = (1,)
-    output_field_class = TextField
+    output_field = TextField()
 
     def __init__(self, expression, version=2, precision=8, **extra):
         expressions = [version, expression]
@@ -189,7 +186,7 @@ class AsKML(AsGML):
 
 
 class AsSVG(GeoFunc):
-    output_field_class = TextField
+    output_field = TextField()
 
     def __init__(self, expression, relative=False, precision=8, **extra):
         relative = relative if hasattr(relative, 'resolve_expression') else int(relative)
@@ -281,7 +278,7 @@ class ForceRHR(GeomOutputGeoFunc):
 
 
 class GeoHash(GeoFunc):
-    output_field_class = TextField
+    output_field = TextField()
 
     def __init__(self, expression, precision=None, **extra):
         expressions = [expression]
@@ -345,7 +342,7 @@ class Length(DistanceResultMixin, OracleToleranceMixin, GeoFunc):
 
 
 class LineLocatePoint(GeoFunc):
-    output_field_class = FloatField
+    output_field = FloatField()
     arity = 2
     geom_param_pos = (0, 1)
 
@@ -355,17 +352,17 @@ class MakeValid(GeoFunc):
 
 
 class MemSize(GeoFunc):
-    output_field_class = IntegerField
+    output_field = IntegerField()
     arity = 1
 
 
 class NumGeometries(GeoFunc):
-    output_field_class = IntegerField
+    output_field = IntegerField()
     arity = 1
 
 
 class NumPoints(GeoFunc):
-    output_field_class = IntegerField
+    output_field = IntegerField()
     arity = 1
 
 
diff --git a/django/contrib/postgres/aggregates/statistics.py b/django/contrib/postgres/aggregates/statistics.py
index 19f26ec53c..5f5ddc4757 100644
--- a/django/contrib/postgres/aggregates/statistics.py
+++ b/django/contrib/postgres/aggregates/statistics.py
@@ -8,7 +8,9 @@ __all__ = [
 
 
 class StatAggregate(Aggregate):
-    def __init__(self, y, x, output_field=FloatField(), filter=None):
+    output_field = FloatField()
+
+    def __init__(self, y, x, output_field=None, filter=None):
         if not x or not y:
             raise ValueError('Both y and x must be provided.')
         super().__init__(y, x, output_field=output_field, filter=filter)
@@ -37,9 +39,7 @@ class RegrAvgY(StatAggregate):
 
 class RegrCount(StatAggregate):
     function = 'REGR_COUNT'
-
-    def __init__(self, y, x, filter=None):
-        super().__init__(y=y, x=x, output_field=IntegerField(), filter=filter)
+    output_field = IntegerField()
 
     def convert_value(self, value, expression, connection):
         if value is None:
diff --git a/django/contrib/postgres/functions.py b/django/contrib/postgres/functions.py
index 36b32e0751..819ce058e5 100644
--- a/django/contrib/postgres/functions.py
+++ b/django/contrib/postgres/functions.py
@@ -3,17 +3,9 @@ from django.db.models import DateTimeField, Func, UUIDField
 
 class RandomUUID(Func):
     template = 'GEN_RANDOM_UUID()'
-
-    def __init__(self, output_field=None, **extra):
-        if output_field is None:
-            output_field = UUIDField()
-        super().__init__(output_field=output_field, **extra)
+    output_field = UUIDField()
 
 
 class TransactionNow(Func):
     template = 'CURRENT_TIMESTAMP'
-
-    def __init__(self, output_field=None, **extra):
-        if output_field is None:
-            output_field = DateTimeField()
-        super().__init__(output_field=output_field, **extra)
+    output_field = DateTimeField()
diff --git a/django/contrib/postgres/search.py b/django/contrib/postgres/search.py
index 889f5253c3..a14d510208 100644
--- a/django/contrib/postgres/search.py
+++ b/django/contrib/postgres/search.py
@@ -202,10 +202,12 @@ SearchVectorField.register_lookup(SearchVectorExact)
 
 
 class TrigramBase(Func):
+    output_field = FloatField()
+
     def __init__(self, expression, string, **extra):
         if not hasattr(string, 'resolve_expression'):
             string = Value(string)
-        super().__init__(expression, string, output_field=FloatField(), **extra)
+        super().__init__(expression, string, **extra)
 
 
 class TrigramSimilarity(TrigramBase):
diff --git a/django/db/models/expressions.py b/django/db/models/expressions.py
index db62541559..1937ca16c7 100644
--- a/django/db/models/expressions.py
+++ b/django/db/models/expressions.py
@@ -467,8 +467,10 @@ class DurationExpression(CombinedExpression):
 
 
 class TemporalSubtraction(CombinedExpression):
+    output_field = fields.DurationField()
+
     def __init__(self, lhs, rhs):
-        super().__init__(lhs, self.SUB, rhs, output_field=fields.DurationField())
+        super().__init__(lhs, self.SUB, rhs)
 
     def as_sql(self, compiler, connection):
         connection.ops.check_expression_support(self)
@@ -692,8 +694,7 @@ class Star(Expression):
 
 
 class Random(Expression):
-    def __init__(self):
-        super().__init__(output_field=fields.FloatField())
+    output_field = fields.FloatField()
 
     def __repr__(self):
         return "Random()"
@@ -1017,6 +1018,7 @@ class Subquery(Expression):
 
 class Exists(Subquery):
     template = 'EXISTS(%(subquery)s)'
+    output_field = fields.BooleanField()
 
     def __init__(self, *args, negated=False, **kwargs):
         self.negated = negated
@@ -1025,10 +1027,6 @@ class Exists(Subquery):
     def __invert__(self):
         return type(self)(self.queryset, negated=(not self.negated), **self.extra)
 
-    @property
-    def output_field(self):
-        return fields.BooleanField()
-
     def resolve_expression(self, query=None, **kwargs):
         # As a performance optimization, remove ordering since EXISTS doesn't
         # care about it, just whether or not a row matches.
diff --git a/django/db/models/functions/base.py b/django/db/models/functions/base.py
index e1d7938eac..4b4d4f4ea5 100644
--- a/django/db/models/functions/base.py
+++ b/django/db/models/functions/base.py
@@ -142,9 +142,7 @@ class Length(Transform):
     """Return the number of characters in the expression."""
     function = 'LENGTH'
     lookup_name = 'length'
-
-    def __init__(self, expression, *, output_field=None, **extra):
-        super().__init__(expression, output_field=output_field or fields.IntegerField(), **extra)
+    output_field = fields.IntegerField()
 
     def as_mysql(self, compiler, connection):
         return super().as_sql(compiler, connection, function='CHAR_LENGTH')
@@ -157,11 +155,7 @@ class Lower(Transform):
 
 class Now(Func):
     template = 'CURRENT_TIMESTAMP'
-
-    def __init__(self, output_field=None, **extra):
-        if output_field is None:
-            output_field = fields.DateTimeField()
-        super().__init__(output_field=output_field, **extra)
+    output_field = fields.DateTimeField()
 
     def as_postgresql(self, compiler, connection):
         # Postgres' CURRENT_TIMESTAMP means "the time at the start of the
@@ -178,13 +172,7 @@ class StrIndex(Func):
     """
     function = 'INSTR'
     arity = 2
-
-    def __init__(self, string, substring, **extra):
-        """
-        string: the name of a field, or an expression returning a string
-        substring: the name of a field, or an expression returning a string
-        """
-        super().__init__(string, substring, output_field=fields.IntegerField(), **extra)
+    output_field = fields.IntegerField()
 
     def as_postgresql(self, compiler, connection):
         return super().as_sql(compiler, connection, function='STRPOS')
diff --git a/django/db/models/functions/datetime.py b/django/db/models/functions/datetime.py
index a8e1ca45c1..c6614a14c2 100644
--- a/django/db/models/functions/datetime.py
+++ b/django/db/models/functions/datetime.py
@@ -2,14 +2,13 @@ from datetime import datetime
 
 from django.conf import settings
 from django.db.models import (
-    DateField, DateTimeField, DurationField, IntegerField, TimeField,
+    DateField, DateTimeField, DurationField, Field, IntegerField, TimeField,
     Transform,
 )
 from django.db.models.lookups import (
     YearExact, YearGt, YearGte, YearLt, YearLte,
 )
 from django.utils import timezone
-from django.utils.functional import cached_property
 
 
 class TimezoneMixin:
@@ -31,6 +30,7 @@ class TimezoneMixin:
 
 class Extract(TimezoneMixin, Transform):
     lookup_name = None
+    output_field = IntegerField()
 
     def __init__(self, expression, lookup_name=None, tzinfo=None, **extra):
         if self.lookup_name is None:
@@ -75,10 +75,6 @@ class Extract(TimezoneMixin, Transform):
             )
         return copy
 
-    @cached_property
-    def output_field(self):
-        return IntegerField()
-
 
 class ExtractYear(Extract):
     lookup_name = 'year'
@@ -183,17 +179,18 @@ class TruncBase(TimezoneMixin, Transform):
             raise ValueError('output_field must be either DateField, TimeField, or DateTimeField')
         # Passing dates or times to functions expecting datetimes is most
         # likely a mistake.
-        output_field = copy.output_field
-        explicit_output_field = field.__class__ != copy.output_field.__class__
+        class_output_field = self.__class__.output_field if isinstance(self.__class__.output_field, Field) else None
+        output_field = class_output_field or copy.output_field
+        has_explicit_output_field = class_output_field or field.__class__ is not copy.output_field.__class__
         if type(field) == DateField and (
                 isinstance(output_field, DateTimeField) or copy.kind in ('hour', 'minute', 'second', 'time')):
             raise ValueError("Cannot truncate DateField '%s' to %s. " % (
-                field.name, output_field.__class__.__name__ if explicit_output_field else 'DateTimeField'
+                field.name, output_field.__class__.__name__ if has_explicit_output_field else 'DateTimeField'
             ))
         elif isinstance(field, TimeField) and (
                 isinstance(output_field, DateTimeField) or copy.kind in ('year', 'quarter', 'month', 'day', 'date')):
             raise ValueError("Cannot truncate TimeField '%s' to %s. " % (
-                field.name, output_field.__class__.__name__ if explicit_output_field else 'DateTimeField'
+                field.name, output_field.__class__.__name__ if has_explicit_output_field else 'DateTimeField'
             ))
         return copy
 
@@ -241,9 +238,7 @@ class TruncDay(TruncBase):
 class TruncDate(TruncBase):
     kind = 'date'
     lookup_name = 'date'
-
-    def __init__(self, *args, output_field=None, **kwargs):
-        super().__init__(*args, output_field=DateField(), **kwargs)
+    output_field = DateField()
 
     def as_sql(self, compiler, connection):
         # Cast to date rather than truncate to date.
@@ -256,9 +251,7 @@ class TruncDate(TruncBase):
 class TruncTime(TruncBase):
     kind = 'time'
     lookup_name = 'time'
-
-    def __init__(self, *args, output_field=None, **kwargs):
-        super().__init__(*args, output_field=TimeField(), **kwargs)
+    output_field = TimeField()
 
     def as_sql(self, compiler, connection):
         # Cast to date rather than truncate to date.