It seems like you want to set up faceted search results which is something you can set up with Azure Search as described here: https://docs.kentico.com/k11/configuring-kentico/setting-up-search-on-your-website/using-azure-search/integrating-azure-search-into-pages.
If you'd like to do this with local Smart Search indexes, it would most likely require a custom web part based on the out-of-box Smart Search Filter web part. The system stores search results in SearchContext.CurrentSearchResults, so you can check the results in your custom code and display the filtering options you'd like.
It may even be possible to accomplish this by placing a custom macro method in the out-of-box Smart Search Filter web part's Values property, which uses SearchContext.CurrentSearchResults to generate the filter options. I haven't tested this and there might be some issue with the page/control lifecycle.