If you manage custom fields in WordPress using Advanced Custom Fields, and you want to use WPGraphQL to get a list of posts filtering by
Query what you need. Get exactly that.
With GraphQL, the client makes declarative queries, asking for the exact data needed, and in exactly what was asked for is given in response, nothing more. This allows the client have control over their application, and allows the GraphQL server to perform more efficiently by only fetching the resources requested.