There are some pretty squirrely claims making the rounds about what the Presidential Records Act does and does not require. In brief: presidents are legally required to turn over all documents relating to their work in office; the obligation attaches at the time their term ends; there isn’t any sort of further negotiation period.
All that is aside from other issues in the Trump case, such as that you can’t just blow off a grand jury subpoena, and you can’t falsely certify to federal officers that you’ve turned over all responsive documents when you’ve actually instructed your valet to hide a lot of them. These are not close legal issues.
Trump didn't get charged with illegal possession over the 197 docs he gave back to the archives when asked. That matches up with how Biden, Pence, etc. were treated. Give back voluntarily = no rap.
Trump is facing charges because he chose to lie to the feds and hide documents.