This is a sample solution that can enable the variant properties as facets for product listing and product search in sitecore experience commerce.

Variants in sitecore commerce are stored as components in a sellableitem and information about the variants is not indexed in sitecore and without customisations it is not posisble to use variant properties to be used for faceting.

1. Integrate the Plugin.Sample.CatalogExtension in to your current commerce engine solution. This will enable the variant properties Sizes, Colors and Styles to be available as properties on the sellable item template and maps the distinct variant properties (Size, Color, Style) to the variant properties.
2. Once the customisation is deployed to commerce engine roles. Update the Commerce Data templates in sitecore. This should have created a custom component template with variant properties (Sizes, Colors, Styles)
3. Copy the config file Project.Sample.VariantProperties.config (config) to sitecore, this will register the variant properties with the correct data types that will enable the usage of variant property data as facets.
4. Download and install the package Commerce Variant Properties.zip (Package), this will setup the facet items in sitecore (Commerce Colors, Commerce Sizes, Commerce Styles).
5. Publish changes and re-build web and master indexes.
6. To enable the variant properties on Product Listing pages. go to /sitecore/templates/Commerce/Catalog/Commerce Category/__Standard Values add the required variant properties to Runtime Search Facets field. Save and publish changes.
7. To enable the variant properties on Product search page. go to /sitecore/templates/Commerce/Catalog/CommerceSearchSettings/__Standard Values add the required variant properties to Runtime Search Facets field. Save and publish changes.