PlayStation 4 and Xbox One versions of Grand Theft Auto V and Red Dead Redemption 2 will be playable via backward compatibility, along with the most recent versions of L.A. Noire (including the PlayStation VR version of L.A. Noire: The VR Case Files), all previous backward compatible Rockstar Games titles on Xbox One, and all Rockstar Games PlayStation 2 titles currently available on the PlayStation 4 from the PlayStation Store.
If you happen to have a disc copy of any of these games, they’ll still work in your new console. if you have a digital version, you can download that same title on your new console if you’ve tied that game to your PSN or Xbox Live accounts. You can transfer save files as well with USB, or just use cloud saves. Your progress and achievements in GTA Online and Red Dead Online will carry over.