Lets see. The SSD is new, and will be used for games. No need to clean anything, since it's new.
If the only thing on the hard drive you'll be using for his system drive is the operating system, a clean install on the operating system drive is considered ideal, if tedious and time-consuming. If you decide to do a clean install, the OS install will delete existing partitions, as little_me noted.
The only reason I butted in is because I thought that "uninstall one of my sdd drives from my computer and put it in my sons ryzen build" might have referred to a solid-stated drive (cuz it starts with S, see?) and, if it did, IMHO an SSD that gets put in a new machine should be factory-reset instead of just formatted. That way it knows that all of the blocks are unallocated.