Add to cart product numbers

It's a bit hard to explain, I'm trying to add products, all is going well however I want to add a sub product, for instance main product, then sub product 1 (added by size) sub product 2 (added by size) and so on, I can add these my only problem is when I go to the front of the cart is it possible to select the number of products separately.
So I would like to order 4 of size a and 2 of size b, is this possible, if so how

Many thanks in advance

I found an example of what i'm looking to do https://www.cromwell.co.uk/shop/abrasiv ... ern/f/1060 I think they are variants of a product where people can select different amounts of each size.