The Upsell Pop-Up add-on displays a pop-up recommending products for shoppers based on what is in their shopping cart.
In the Debutify Shopify theme, you can create a wide range of product recommendations in the upsell blocks.
How to Add More Upsell Pop-ups
In Shopify admin, click on Online Store.
Select your Debutify Shopify theme and click on Customize.
Click on Upsell Popup.
Click on an Upsell or click on add Upsell.
Add products to Upsell.
Click Save to apply the changes.