Let us show you how to choose the Quantity Type as Select.
Step 1: From the admin dashboard, navigate to Products > All Products.
Step 2: Select the product you want to change the Quantity select type.
Step 3: At the Product data section, select tab Quantity.
Step 4: Choose the Type as Select.
Step 5: Set the value range for that product’s quantity.
Step 6: Hit Update to save you changes.