I think there’s no one “best” coating for a chalk drawing.  The most important consideration is whether you want the drawing to be easy to erase, or difficult.
assistant
You may be referring to “art canvas”.  The composition of art canvas is similar to canvas paper.  However, art canvas has a higher quality of paint adhesion, for a longer period of time.  I suggest that you consider purchasing “gsm art canvas”.
assistant
What is the best kind of coating to protect a chalk drawing I made?
user