For Relay you're basically given no caching out of the box, but you can implement it by essentially hijacking the store's garbage collection to use an LRU cache instead of immediately evicting data when its dependents unmount. The developer experience for client-side schema extensions is similarly immature, but it is possible.
If you need all this functionality and aren't comfortable diving into the trenches, you'll have an easier time with Apollo (assuming everything works as advertised).
It's great for pull down refresh lists etc and I even had success doing dynamic insertion when an item in another view was updated (though I had to use a different graphql client to do the inserts ironically) but it was sold as replacing all need for redux for example for state management and that it would sync seamlessly with a graphql backend and unfortunately (maybe it was me) couldn't work out how to do that so ended up using redux as well.
What I was lead to expect is that you subscribe to a store which is dynamically filled and updated by Apollo (which handles synchronising local and remote and loading from scratch etc).
Apollo has more advanced configuration options, and I think they're confusing to grasp at first. But I do think Apollo cuts down on the amount of state management you need to do for a typical app by about 2/3rds or more.
An example of that is updating the state after mutations that modify lists (e.g. creates or deletes). It's up to the developer to remember all other queries that could be affected by a mutation and to update them manually after the mutation completes (more info: https://github.com/apollographql/apollo-client/issues/3505 and https://www.apollographql.com/docs/angular/features/cache-up...). If you add a new component that performs a query that could be affected by a previous mutation, you have to remember to also go back to that mutation and update your query from it. With ngrx (or redux), the consistency is baked in, and part of the beauty of it is that if you update the state, anyone who happens to be reading that state will get updated automatically.