Basel theme suggests expanded options for the Product categories presentation. The product categories menu can be presented in the shop page title, in the search form, Browse categories element in the header.
Product Categories menu in the Shop page title:
There is an option to show the Product categories in the shop page heading which is configured in the Theme Settings > Shop Page > Shop page layout > Shop page title option. Title Demo: https://demo.xtemos.com/basel/shop/?shopmasonryalt
Option “Categories in page title” will show the Product categories menu generated automatically based on all categories existing in the shop. There is the option to hide empty categories and, starting from 5.4.0 version the option to select the categories to show is provided. These options are in the Theme Settings > Shop Page > Shop page layout > Shop page title option.
By default, sub-categories will be displayed as the drop-down list: