That's an odd question
I don't think chibis and someone's style can be put in the same category~_^
Chibi's are a trick to add more fun to the picture..Someone style is personal, something you develop in time by drawing more :o
If the art in a show is similar to another (ie ranma1/2/inuyasha) it's because it's the same artist not because there's a style that artists learn and then aply it to their works.
If you want to learn to draw exactly something from another anime you take some pictures of it and then study them...See what makes them different, the line the artist uses, if he likes to exagerate anything, hair/eyes shape....etc
This kind of studying usually best aplies to someone with drawing experience. If you look at the picture and just copy it, it might look like the original but you won't uderstand why it's done like that. That's why a study like that is good.
But I don't recomend you to try to copy someone's style..You can do it once ore twice but if you do it to every drawing you make you'll loose your style. It happened to someone I knew ,and trust me, it's not really pleasant to see that when you're doing an original character it looks just like a specific anime character/style.
Edit: How rude of me ..Welcome to the forums!