Plex has a reverse proxying service and can do upnp for you so it works with dynamic IPs out of the box with no need for a domain or forwarding ports. It defaults to upnp and falls back to the Plex hosted reverse proxy which also uses a dynamically generated subdomain and gives you a free SSL cert. Granted I prefer to host my own reverse proxy anyway with my own domain (when I had a static IP I just forwarded a port and set up an A record) but out of the box Plex does make it much easier for a non technical user to hit the ground running.