I just recently got the z fold3 as I fancied something different to the regular s series I get, plus I use the phone for games, but my question is this : will the screen get damaged if it is left folded for too long?
I'd check for reviews of the phone online. There have been quality issues with folding screen phones in general. You can also check with Samsung about their testing to see what methods they used to test durability.
Considering the phone was only out since Aug of 2021 I doubt there is a long enough reliability history of it to know much.