When we are going to manage the collections using sub-category in the Shopify projects, we can implement it using tags.
In this case, we will likely need to implement the filtering functionality. But the default filtering url doesn’t work for sub categories. In order to figure out this issue, we can adjust the URLs properly to get the filtering products as following
∆ Filter URL for normal collection
mystore.com/collections?constraint=[tag]+[tag]
∆ Filter URL for sub category in collection
mystore.com/collections/[collection-handle]/[sub-category]+[tag]+[tag]
∆ Not working URL for sub category in collection
mystore.com/collections/[collection-handle]?constraint=[tag]+[tag]