Can you learn illustration without sketching?

I study animation design. I think there are many forms of illustration. The reason to learn the most basic sketch color is not only to let you know the basic structure of objects and the feeling of light and shadow, but also to understand the composition of lines. But there are also many amateur illustrators who can draw good illustrations, because they draw from another angle and put aside the so-called theory, but express what they want to express most intuitively. These are exactly what today's academic school may have to hone for many years, because too many frameworks bind the heart. I suggest you buy more picture books of your favorite style, read more books and see how lines and colors are used to enhance aesthetics. Then try to start painting, and then start from what you think needs to be strengthened, so that you can learn according to your actual situation.