You can incentivize your customers to make bigger purchases by offering volume discounts via the Product variants feature.
In the Editor, go to the Webshop tab. In the menu on the left, click on Products, then select the product you want to edit.
In the Edit product dialog, under Product variants, click on the Add product variant button.
Add product variants for different quantities of the product, as shown in the example below, and click on Save.
Enter prices for each quantity, and click on Save.