If you bought the PS5, to catch up on PS4 games, well in my opinion, there's plenty to catch up with (assuming you don't play using X-BoX One and PC).
Though personally speaking, I used the PS4 games to catch up on PS4/3 games, plus bought PS2 games that were ported in the PS4. In total, i have about 90 games in my PS4 library. I'm still waiting for Red Dead Redemption 1 to go on sale and might use it for the PS4 later on.
I plan to buy the PS5 in the summer and so far, I only have 11 games (2022 to early 2024) to catch up with. And its really not a lot. 13 if I add Hitman 3 (which i already bought its ps5 version) and the Astro free game. I have already finished Guardians and Miles Morales in the PS4, and bought RE Village since they were available for the PS4 anyway.
I hope the neXt Assassin's Creed game comes out later this year and GTA VI in early 2025. A lot of the big Sony first party games are still years away.