Shopify doesn't allow nested collections (collection within a collection) which can be very constrained for many stores. With this implementation, you'd be able to form a multi-tier category navigation, by creating a page with a list of collections that you simply choose.
Getting your navigation set up properly will not only help your customers find their way around your website but will also spare you valuable time once you get to add and sort products.
Our experts can help you here. By simply creating a menu (link list) with the collections and/or other subcollection pages for multi-leveling and then creating a new page with the same title as your menu (link list).
Final thoughts
Why make your sub-collections or sub-categories look just like another collection on the site? We do not limit our creativity. Share your expectations, and we will be able to recraft a fully customizable sub-collection template for you.