Rasplex used to be a thing (and was based on OE, then LE): https://www.rasplex.com .. but that died out.
There was also a "Plex Embedded" image for RPi/x86_64 devices (originally on OE, then LE) created by Plex staff that combined our base OS with an auto updating Plex binary, but I think that also died out over time, and I don't frequent the Plex forums these days.
I'm not sure if Plex has a dedicated Linux app now (or what would be required to run one). I have the impression that over time they moved to a more controlled (and thus restricted) client experience. If something exists it's all do-able, but that requires time/effort and the Plex universe seems to be more about desktop OS or native apps on TV's these days.