Honestly, if you approach it with the intent of getting better faster, you can become a very proficient artist in a very short amount of time. The issue is, of course, that we as artists usually want to enjoy the process of drawing, and not just the product, and improving at a rapid pace involves making yourself draw things that are unfamiliar, challenging or "boring".
At the end of the day, all an art style is, is the translation of real-life objects into symbols - more specifically, their volume into lines. If you learn how to understand 3D volume and then put that paper into 2D lines, you can draw in whatever style you want. Training your mind to understand this is probably a matter of months, if not weeks. But, again, they're not fun weeks of drawing fun cute waifus (or husbandos), it's weeks of drawing boxes and spheres and simplified clay busts to understand how light interacts with the planes of the objects to define their depth. That's all you really need to begin stylizing, because you'll be able to understand what the artists you admire were doing when they drew their lines in a particular way, and be able to replicate and build on their thought process.
If you're serious about improving quickly, I recommend a study and reward approach - sit down and drawn "boring" stuff for 15-30 minutes. Study a shape and make yourself draw what you see, not what you think you see. Plop your phone down in front of you and just draw it, for example. Then afterwards, as a reward, draw whatever your heart desires for however long you can bear it. Do this for a few months, and you will notice an incredible improvement. The key is to always choose to draw something you haven't drawn before, because that's how your mind develops the ability to "see" like an artist (and this is why people who begin drawing a comic will often find themselves improving rapidly - because they HAVE to draw things they're not comfortable with in order to progress their story). You can also study color theory and practice drawing in different mediums and read about composition and learn your anatomy and do gesture drawings and blah blah -- all of those will also make your stylized art better, but I think all of that can be learned concurrently with developing your own style. There isn't really a substitute for understanding the volume of objects, though.
