The query text and plan are stored in two separate tables, sys.query_store_query_text and sys.query_store_plan, respectively. The text is stored as a nvarchar(max) data type, and the plan is stored as varbinary(max). This means that the data can be mined, looking for patterns and explicit use of objects. Want to know what queries use an index? Look for it in the plans. Want to know what queries have a RECOMPILE hint on them? Look for it in the query text. Anything you want to find with regard to query text or plans is there, you just have to know how to query the data.
It’s hard to tune queries if you don’t know what’s running.