Sony's just announced a curated selection of great PS4 games that you'll be able to download and play on PS5 on launch day.
It's called the PlayStation Plus Collection. A lot of the games are from PS4's first party - expect Uncharted 4, Infamous, The Last Guardian and that sort of thing. There's also Fallout, Batman Arkham Knight and Mortal Kombat, amongst other third-party titles.
It's sort of Game Passy, and sort of a catch-up episode for anyone who slept through the last console generation. Here's a trailer!