How and where did they learn all those things?
The majority of people tend to learn the following ways.
- Tutorials (written and video)
- Online training courses (paid)
- Example content (free or paid).
What you usually do not find here are users who got their training in professional art schools (as the vast majority of people who use Blender can’t afford them anyway).
You have started the right way: asking a question.
From there: do the advice given you. Obsessively.
Do the tutorials. Practice the tutorials on your own materials and projects.
Put your work up for critique. Practice the things they suggest. Obsessively.
Classical training is exceptionally helpful: a real-life sculptor, painter, media artist, etc.
Go to shows. Show your work. Make poster quality work and print it out. Sell it.
The path has been shared many a time. It’s the obsessive part that many miss.
Most of them have just started out in Blender, and are amazing at modeling and texturing. The newbies are usually the best.
Practice, practice, practice. The same as any other skill.