Ok the main categories page I fixed it. Thank you.

By clicking on one of the categories, I would like to be redirected to a page with all the sub-categories.
Let me explain: the “Museum” category has as subcategories a series of artists such as “Modigliani” “Da Vinci” “Klimt” … is it possible?

I am forwarding you some screenshots of a site, I would like to have it with this structure.