**extra for django.db.models.functions?

Question

Django

Hello everyone!)
Django has database functions: Coalesce, Cast, and so on. Some allow named arguments to be passed. For example:

class Coalesce(*expressions, **extra)

And this moment interests me. What named parameters can be fed there (not only in Coalesce)? I know, you can pass output_field.
It looks like I'm not entirely clear about the further transformation of ORM to SQL.
Please advise.