Most, nearly all games will have unique saves for each user. My son sometimes goes into a game, his save isn’t there, and realizes he needs to switch users.
When we all play a game together, we typically use my account as the “main” account, unless that game is particularly important to one of the kids.
We make all purchases through the main account as well just for consistency. The purchase is tied to the account. When we upgraded to PS5 from PS4, all of the games were accessible from the account.
Trump has a famous line whining about America only getting immigrants from the “shithole countries”. Wonder why, dude.