There’s a bunch of great content on YouTube. Some jeep channel has some stuff, ham radio crash course, ham radio 2.0 etc. all have gmrs content and some antenna stuff.
You can get really in the weeds with some of the technical stuff.
if you want training on how to use radios in different situations, you can search you tube for terms like “Pace plan” “soi” etc. TechPrepper has some good stuff on that, but you might look for some in person training since it’s hard to do that kind of thing by your self.
GMRS is more based around bring your contacts than making new contacts with strange men.