Hi!
I am told that FacetWP is probably the best one, but I am not too familiar with it. I don’t know if it works on existing pages, or you need a custom page for it though.
The plugin can be used as a filter as well of course, but currently it is not yet capable of filtering archive/result pages.
It is possible to create layouts like these:
– https://ajaxsearchpro.com/staff-search-filter/
– https://ajaxsearchpro.com/property-search/