Cross-sell recommendations; product sets
In many industries you can increase the value of carts by presenting products that make up a set or somehow complement items already in the cart.
In the retail branch you can create sets based on a certain style, for example shoes, dress and bag. If you present all the products in one photo and show how nice they look together, you can encourage users to buy all of them.
Discount on product sets
Display sets on the cart page, created with complementary products at a promotional price. This is a great way to increase sales, especially when the products offered are closely related to the main product (laptop and mouse, phone and headphones). If they create a set together it will be easier to encourage customers to buy them together.