I learned by looking at screenshots of anime I liked and trying to draw it as close as possible to the picture without tracing. I kept doing that until I learned how to draw the basics, then I used more general anime references and picked and chose what things I did and did not like to draw (for example, I like semi-realistic eyes more than stylized ones), and I combined it. That would be my style. Then I started branching into different styles and types of art, and I kept including that into my style. I still do that. Now, I can draw realism, semi-realism, anime, cartoon, and some chibi*. It just depends on how much time you are willing to spend drawing. If you actually motivate yourself and focus on improving imperfections, you can learn pretty easily. Also- no artist ever stops learning. You improve with every drawing.
*So a quick explanation of the types I mentioned-
Realism- For realism, making your art so real-looking, it looks like a picture.
Semi-realism- This has different groupings. But I typically do more realistic proportions, while still drawing things anime style. For example, anime eyes, but smaller.
Anime- Your general anime, SAO stuff. A good place to start, it's in the middle of stylization (extra cartoony look) and realism.
Cartoon- Yes, technically anime is also a cartoon, but I mean more along the lines of like, Daria, MLP, Clifford, Littlest Pet Shop, etc. More stylized.
Chibi- Typically just for short comic strips. Super stylized, small body, head the same size as the rest of the body, very little if any shading. Gacha is an example of a chibi.
Two websites that have really good references-
https://www.animeoutline.com (Has references and tutorial guides)
https://drawingref.com (Just references, but really good ones!)
