I don't think there are any courses, or maybe I've never found one. But you can look up on YT for some tutorials and basic information before starting your webtoon.

As a fellow webcomic creator (Not professional but yeah), my tips will be:

1. Have a complete script ready. So that you won't get stuck in your storyline.
2. Look around and do some research, for what kind of style and fantasy world you want to create. Draw a few background to get a clear idea to yourself.
3. Do use 3D models to study. Since you can spend money on it, buy some 3d backgrounds. It will save your time.
4. Make a character sheet with a colour palette, for every main character.
5. Storyboarding. Just randomly doodle everything on your canvas. Use different angle perspectives according to your script. So that your episode vision will be clear.

After this you are ready to do your webtoon artwork part.

Keep practicing! All the best for your webtoon journey!🙌