Search and Discovery - Filters

Hi All

I am setting up a new store and wanted to ask about these filters I can add to collection pages.

As an example, I am setting up Shampoos and of course, they all have a scent. This filter works OK if a product has variants called Scent.

But I want to be able to filter by scent if a product only has one variant. IE I do not want to have to make a variant to provide a scent filter for it. Otherwise, I get a single variant selector on the product page.

So, the question is how can I have a filter that works on scent choices for multiple variant products and single products?

Thanks

you may add a tag or type on the product for this scent word.