Does "deferred field" imply under-the-hood `.defer()`?

[danlynkew]

Django provides the .defer() optimization for querysets. This optimization drops the deferred field from the SQL query sent to the database. That is, Country.objects.first().defer('states') means "don't even ask the database for the country's states field."

drf-flex-fields's documentation reads:

Alternatively, you could treat country as a "deferred" field by not defining it among the default fields. To make a field deferred, only define it within the serializer's expandable_fields.

When drf-flex-fields is used to "defer" a field in this way, is Django's .defer() actually used under the hood?

Asked another way: will the default response for the below serializer retrieve a country's states field from the database or not?

class CountrySerializer(FlexFieldsModelSerializer):
    class Meta:
        model = Country
        fields = ['name', 'population']

        expandable_fields = {
            'states': (StateSerializer, {'many': True})
        }