This app Ultimate Filter & Search https://apps.shopify.com/ultimate-search-and-filter-1 can filter by variants. It has an advanced feature to show variants as separate products based on specific options (color, style, size) on Collection, Instant Search, Search results page. This will give your customers a seamless experience when they want to search for something. It can show the matching variant image with search term and filter selection. In addition, you can merge similar values, i.e. pink, blush pink, lilac into one common value "pink" in the filter.
You can duplicate the live theme and set up the app into the copied one. It will not affect other themes in your store, so you'll have time to test the feature and setup.