How does one sell a 4 pack in home and garden items? Not being brand owner.

We have a product that is selling relatively well, it’s small and at a low price point, and we want to sell it in a 4-pack format. Let’s say it’s a lighting fixture. What would be the correct way to sell the product that way? Are we forced to create a new UPC barcode for it? Is there any way at all to do it? Creating another product state does not give us a sale quantity input option, only an inventory quantity input.