Like this current one that is already in place:

/product-category/schools/?orderby=popularity&product-tag=testingtag

is it possible or would i need to add rewrite rules?

thanks

That is super close. Change the product-tag to product_tag and that should let you get products with this tag inside this category.

Something like this:

https://site.com/product-category/clothing/?product_tag=shirt

Let us know if you have any trouble.

Hopefully, you were able to find a solution to your problem! If you have further questions, please feel free to open a new topic.

Cheers!