Enabling Query Store with default values is equivalent to this Transact-SQL statement:
ALTER DATABASE WideWorldImporters SET QUERY_STORE = ON ( OPERATION_MODE = READ_WRITE, MAX_STORAGE_SIZE_MB = 100, DATA_FLUSH_INTERVAL_SECONDS = 900, INTERVAL_LENGTH_MINUTES = 60, CLEANUP_POLICY = (STALE_QUERY_THRESHOLD_DAYS = 367), QUERY_CAPTURE_MODE = ALL, SIZE_BASED_CLEANUP_MODE = OFF, MAX_PLANS_PER_QUERY = 200 );
The default configuration is good for small databases or when you want to enable the feature and learn about it with a real query workload. However, for large databases and volatile database workloads you might need to change values for some Query Store options.