Unfortunately, there isn't a clean way to do this in graphene (or any other library that defines a static schema through class attributes like attrs or django-rest-framework's Serializer).

An object like Input is used by Graphene to build a static schema for GraphQL. Having a static schema is super beneficial for tooling and API evolution purposes. The fact that a field is required (or optional) is part of that static schema. Meaning, if something is required on an object, it is required for all instances of that object. The only way to have a field required or not required in different contexts is to create a different object for each context.

Your Input example is simple enough that you might be annoyed to have some code duplication but just live with it. If you want to get creative, you might be able to apply metaprogramming to define a factory method to create these similar Input classes but with different name and value for required parameter.

def build_input(is_create=True):
    class Input(graphene.InputObjectType):
       class Meta:
           name=f'{prefix}StoryInput'

        title = graphene.String(required=is_create)
        author_name = graphene.String(required=is_create)

    return Input

CreateStoryInput = build_input(is_create=True)
StoryInput = build_input()

Generally, I would prefer to use a more repetitive, explicit implemention though. Good luck!

ya see Lee Byron's response to basically the same request in JS. graphql/graphql-js#207 (comment)

Closing this issue because (until this is defined in the GraphQL spec) it's not going to get implemented in Graphene (sorry 😞 )