You are right. I started by using the plugin. But I remembered that in the past the plugin was updated more slowly than the pkg updates. So, I've installed it in a blank jail manually and this should perhaps be in a different forum section.
That said, having installed and tested the plugin, I could see that it was actually a newer version than the latest pkg update. I'm wondering if there is a way to get updated builds more quickly (like there is with some software on Ubuntu, etc.)?
I just recently removed all of my jails to rebuild them in 11.3-Beta. So, I think I lost track of what I did to optimize previously. On 11.2, it seemed like I could just use pkg update/upgrade and have the latest Plex within a few days of release.