20% off a specific product or collection (single-item alternative)

Create an Advanced Discount Code using a Product Discount module: set a 20% percentage discount and target specific product(s) or a collection/variant set. This will apply 20% to those selected items (you can encourage customers to add only one qualifying item). If you must automatically apply the discount to the most expensive item or enforce a single-item cap per order, that requires Shopify Scripts (Shopify Plus) or a custom app/server-side solution — functionality not supported by Discounty’s Advanced Discount Code modules.