You can filter out products that are not in stock from search results or on category pages; it's called the 'In-stock toggle' and looks like this:

When it's toggled 'on', it looks like this, and shows only products that are in stock after your search or in your category:

This feature can be accessed on category pages and search results, allowing you to filter out products currently out of stock when sorting by price, low to high, and other criteria. This enhancement significantly improves the site's filtering capability.