A book that I've found quite helpful: Music Principles for the Skeptical Guitarist by Bruce Emery.
Look up also Desi Serna's channel on Youtube.
https://www.youtube.com/channel/UC2M...3wEJH5EDJ7sVIQ
Justin Guitars stuff is pretty good.
Most of the theory stuff turns my brain into soft mushy oatmeal after about 15 minutes. Bruce's book was more accessible. It's worth the effort regardless in my opinion.