This is a way to filter "discounted (sale) products" on Shopify collections and search result pages. Since the presence or absence of a discount price itself cannot be set as a filtering condition, "tags" are usually used. If you use the app, you can automatically add and remove tags just by setting the discount price.
How to make it possible to filter "sale (discounted) products" on collections and search result pages
[Settings Step 1] Set up "Shopify Search & Discovery" from the "Online Store" sales channel menu and add "Tags (detailed filtering)" to the filtering conditions
[Setting Step 2] Set the discount price for the target product and add tags such as "sale"
[Additional Information] How to automatically add and remove tags after setting a discount price
