Advanced Custom Fields, or ACF for short, enables users to add Field Groups, either using a Graphical User Interface, PHP code, or local JSON to various screens in the WordPress dashboard, such as (but not limited to) the Edit Post, Edit User and Edit Term screens.
Whatever method you use to register ACF fields to your WordPress site should work with WPGraphQL for Advanced Custom Fields. For the sake of simplicity, the documentation below will primarily use the Graphic User Interface for examples.