Arc System Work’s next fighting game Guilty Gear Strive will be coming to PS4 and PS5 (as well as PC). If you intend to pick it up on PlayStation, there’s a free next-gen upgrade. This is detailed in the FAQ page for the game.
Just like in many cross-gen games, buying a PS4 copy of Guilty Gear Strive will let you download a PS5 version of the game. DLC will also be carried over to the next-gen console. Matchmaking will have cross-play between PS4 and PS5 players. Unfortunately, PC players don’t get cross-play.
The PS4 version of Guilty Gear Strive is also backwards-compatible on PS5. Not sure why would you want to do it since you should have the free upgrade and the PS5 version goes over 1080p resolution plus faster load times, but it’s possible.
Guilty Gear Strive launches on April 9, 2021 for the PS4, PS5 and PC (Steam). It will include a story mode and 15 characters on launch.