lol I feel the way you feel when you saw those cool scenic images on those videos, they're really nice. I actually tried replicating one, failed miserably. You can try replicating it because thats how artist start through references, but don't expect to finish it in one day with great results.

I think you should look into painting traditionally, because most of those images use textured paint style with little to no lines, idk what the term is. But since buying art supplies can be expensive just try using paint brushes digitally, with different types of strokes and all that stuff. Depending on the program, I use Sai, you can change the setting of the brushes very important in painting.

Once you get into it more and get the hang of it, making your own scenic stuff, look into color theory, using colors that go well together to create emotion or feeling like cool or warm colors kind of thing. And some 1 or 2 point perspectives to finish it off.

Long story short, keep experimenting and practicing.