>it says I should draw for joy
I hear this advice given often, but it's an incomplete piece of advice. The problem is that it's hard to enjoy drawing anything if you're struggling to get a result you want and everything looks like shit. I think this is the primary advantage of starting when you're young; because you don't understand/care as much about how bad you are, so you just keep drawing and practicing anyway instead of getting depressed and stopping. It gets easier when you feel happy with your art more often (though you never truly feel like you're good enough).
In my opinion, and from my personal experience, what you should do is just draw the things you like, and mix exercises and studies in when you feel like it and to help you make the drawings you want. Often you can apply exercises to the things you like. For example if you're learning anatomy, there's not really any reason why you couldn't study that anatomy while drawing cute anime girls, and there's no reason you couldn't change it afterwards to make it look like a robot girl.
>Oh and if I for example want to learn how to draw eyes wont I just copy paste style from tutorials I use for it? When does developing own style happens?
The goal should be to gain the ability to do eyes on your own, to roughly understand how eyes work so you can start making variations of it that you've never copypasted from a tutorial before. You shouldn't try to "gain" and art style, it happens automatically as you learn to interpret and draw things, and hone out the qualities in your art that you don't like and find new details that you do like. Copying other people's drawings (or looking at them very carefully) can be very helpful for finding what stylistic details you like and how to draw it.
Eyes and anime faces specifically are kind of complicated, they're so different from real anatomy that you kind of have to learn a separate understanding for them. When I'm drawing anime style faces, I don't think about the skeleton or bones or eye sockets or whatever, because it just doesn't apply to that art style. Instead I think of the shapes and tricks I've learned from drawing that kind of heads. Many of the details are based on real life though, so the knowledge of it isn't useless, for example the face moves similarly when making expressions. And there's a range of anime styles that are more or less based on reality.