A game that was released last year has absolutely zero knowledge of this 8k PS5 so it’s not going to magically render at 8k or 40% improvement. Some might get a framerate bump if frame sync can be turned off - the game might have been GPU bound and therefore with a better GPU it yields a better framerate. Sometimes. And AI upscaling might give a pseudo > 4k effect but it’s not really true 8k.

A handful of games might get patched to avail of the improved rendering capabilities when they detect PS5 Pro. Minimal stuff really. Maybe the config file will improve draw distance or turn on certain effects like raytraced shadows / reflections when it knows the console can handle it.

Hardly seems worth the vast additional expense especially if somebody already owns a PS5 though. Moreso because Sony are trying to stiff people into buying the cheaper “digital” version which basically means any physical collection won’t work with it.