If you install multiple pms’s on the same win 10 PC’s in separate directories’ and change the ports will that work?
No, that will not work. You have to remember that there are two ports at play here. The “change port” part you mention is just external, internally Plex is hard coded to always listen to 32400. That cannot be changed. Your best option is to use hyper-v or such and create a virtual environment.