How can I create sub-collections in Prestige theme categories?

Store Design
1

hello, I am using Prestige theme from Shopify and would like to have multiple categories with sub-collections. Example: Stilyaga.Style Original would be the name of the category and it would have Women, Men Short Sleeve, Men Long Sleeve, and Caps as sub-collections. How do I do that without involving a fee for an expert? Thank you!