Yes, there's a lot of them. But the only good ones are expensive. You get what you pay for when it comes to PLO knowledge
Books:
- PLO QuickPro (a bit hefty price)
- Tom Chambers books, but they are a bit expensive. (Watch his series on RIO if you're interested).
- Advanced PLO Play by Tri Nyugen (expensive)
RIO has amazing videos, not sure if DeucesCracked is up anymore but a lot of videos on there taught me how to play PLO back in the day. In terms of free videos on YT and stuff, JoeIngram1's content is very good.