Yes, three side seal bags can be used for multi-pack or carton packaging. Due to their compact and uniform shape, these bags are ideal for bundling multiple units together in a box or carton. This packaging method is particularly useful when you want to offer consumers multiple products in one convenient package. 
The flat design of three side seal bags allows them to be efficiently packed into cartons or folding boxes, providing a clean and organized appearance. Additionally, their uniformity makes them easy to handle, store, and ship in bulk. 
This type of packaging is commonly used in industries like food, beverages, beauty, and nutraceuticals, where products are often bundled together for retail or bulk sale.