HELP! Add to cart interaction for items with multiple sizes

Hi All,
I am completing a UX course and am putting the final touches on a beer delivery app. The last thing needed for me to complete my prototype is to be able to choose item sizes (i.e 6 pack, 12 pack, etc) that can be added to the cart with corresponding prices for each size. Attached is a screen shot. The product card has been setup using local variables although I’m not sure if that is the best approach.

in summary: I would like users to be able to select a size, add it to the cart and have the cart reflect the selections made by the user. Is this even possible?

Any information would be greatly appreciated!