How to customize search filters or predicates in AEM search form?

The AEM Search or Asset Filters panel showcases search facets established within the underlying search form through predicates. To introduce additional or varied facets, you can incorporate predicates into the default form or opt for a customized form containing the facets of your preference.

You may visit the AEM documentation "Adding a Predicate" for the detail step by step documentation on this. 

Link: https://experienceleague.adobe.com/docs/experience-manager-65/assets/administer/search-facets.html?lang=en#adding-a-predicate