Tempdb scalability improvement creates multiple files during setup based on number of cores, this will reduce allocation contention on system pages in tempdb.

The Query Store feature helps you to track query plans, runtime statistics and queries/plans history. It also helps you find regressing queries. You can quickly find new queries with multiple plans, identify un-efficient plans and force a better plan.

One way to understand Row Level Security is to think about an implicit WHERE clause for the underlying table.