PS5 & PS4 Sync?

Feb 23, 2021
Just got a PS5 and a few decent games on it (Dirt/Rocket League/etc) on my PSN account. The son-in-law still has a PS4 which is also on my PSN account (he's <13 and we don't want to give him his own account) and he has seen the games I've got on the PS5 and wants them. Happy for him to get the games but just concerned that all the game data/achievements/etc will sync across and he'll lose the ability to gain these and I'll lose out as he'll play it more than I will.

My question is does the game data sync across the platforms or is it tied to the unit?