After ...
Do you know the light and shade clearly? Can you master the structure? If you just want to draw mountains and rivers.
Then you don't have to learn sketch. You draw Chinese paintings.
You know all this.
Then learning to sketch is a waste of time.
If you want to draw a human body, maybe you can try sketching first.
It depends on what you draw, of course.
What is this painting?
Chinese painting is all over.
The foundation is good.
It is ok to learn sketch.
but
,,,
My personal opinion is that you should finish the sketch in the future.
You'd better learn from the tablet,
A person who generally learns Chinese painting and practices writing brush.
The pen is more sensitive than the average person.
You can choose for yourself at such a young age.
I really envy you.