I’m pretty sure that it does, but wanted to confirm that all ports besides 32400 in this: https://support.plex.tv/hc/en-us/articles/201543147-What-network-ports-do-I-need-to-allow-through-my-firewall article refer to the firewall running on the same machine as Plex server, not the firewall on the router PMS is behind.
That is correct. Plex also listens to 32401 on localhost, so you can’t bind anything else to that port.