there are quite many different apps. I have tested several and decided to go ahead with https://apps.shopify.com/product-filter-and-search
The most important feature is that it can deal with both, tags and metafields at the same time.
It can group different values of a filter option, which helps a lot on bigger catalogs.
They also can optionally replace product cards on collection pages. The idea is great, but the predefined templates could be improved. Also the quick shop popup style is not really finalised.
But the filter functionality is exactly what we have expected