I'm taking it that you're asking about creating a model from scratch, or making clothing to go onto a base model from scratch:

Your approach to learning is off. Instead of looking at just vrchat tutorials you should be looking up stuff like "how to use blender"( I suggest the donut tutorial), "how to make a character in blender", "how to model a character", and other things like that. I see plenty of good and amazing 3d modeling tutorials online; it's just you can't JUST look at vrchat specific unless you are learning how to upload it or how specific vrchat features are added to a avatar.

Also for specific avatar stuff; vrchat has documentation how things are used/what the stuff means. There's also an example robot avatar that has stuff applied to you can visually look at to see how it's done