Apart from any taxonomy (category, tag or custom), you can also filter by custom post fields. Technically, anything that’s stored as regular text in the wp_postmeta table can be used.
For example, we’ve used it in combination with our own WP Recipe Maker plugin to filter by recipe cooking times, calories or ratings, as you can see in action here: https://demo.wprecipemaker.com/recipe-index/
Learn more about filtering by custom fields in our documentation.