Can metafields be used for product filters and onsite search?

Yes. Metafields can supply structured product attributes that storefront themes and filtering systems use to help shoppers narrow results. They are especially useful for information that does not fit Shopify’s standard product fields, such as material, fit, compatibility or technical specifications. The key is consistency: use controlled values and the same field definitions across comparable products. Better-structured filters improve human navigation and also make the catalogue easier for search and recommendation systems to understand.