I guess I already do this with "REST" (although I get it's not really called that much if I don't strictly follow 1 resource per request). But I very often just make endpoints that have custom SQL written that touches many tables anyway.
GraphQL was developed at Facebook and Facebook has a massive backend API used by many different teams for many different purposes. In this scenario the trade-offs were apparently worth it because purpose-built endpoints for each feature were likely not scalable and would have required deep knowledge of the full stack to implement.
In teams of 1-10 people with an API that serves a single app controlled by the same team, I'm not convinced GraphQL adds much apart from adding a layer of complexity to the architecture.