If you have a smart mind and tenacious will, and you are diligent, you can make great progress, because diligence can make up for it. If you study art with the same time and energy as others, you may not get good grades-poor talent and slow progress. If you teach yourself completely for four years, you may not get much. If you find a good teacher who graduated from the University of Fine Arts and have enough study time (more than 2 hours a day), it can basically be realized.

As long as you practice often, you can learn sketch well. Learning sketch is mainly to learn the understanding and control ability of composition, light and shade, perspective and so on. It has little to do with creativity.

There is plenty of time in college, but still ask yourself how much you can learn. For zero foundation, it is ok for self-study to reach a certain level. After all, it is four years, but it is difficult to get started. After all, it is a zero foundation. Only relying on online videos or books will make slow progress, and the initial progress is obvious, but the bottleneck will appear as it goes deeper and deeper. For zero-based suggestions, it will be faster to find some expert teachers to give directions. If you are interested in sketching, you can go further and wider in four years. If it's just a whim, it's a tragedy. When you learn a certain degree, you won't ask how much you can learn from sketching.