Grant Fritchey does some housekeeping:
The most important thing to understand here is that Query Store won’t just keep collecting data forever, filling your hard drive. There is a hard limit to how much data Query Store contains. By default, prior to 2019, that was 100mb. After 2019, it’s 1,000mb. You can, of course, adjust this up, or down, as needed on your systems. It’s a database-by-database setting (as so much of Query Store is). You can change this through SSMS:
Even with that limit, there are still several options available to you for when to clean up old Query Store data, whatever the definition of “old” (i.e., time-based or at the user’s whim).