Django Solr (Filter) - a dropdown list for objects, how to implement? or adapt

There is a list of objects displayed by the values of product attributes.

The values of product attributes that are interconnected should be in the form of a dropdown SELECT (OPTION) list/dropdownMenu, i.e. - For example, instead of Size: Medium, Size: Small it should just be

mediumsmall

that these values of the attributes are applied SIZE can be specified inside Templates (Label), i.e. This is not so important, the main thing is how they can be placed in this Select list (dropdown menu).

I want to add that I tried to change the values that are indicated by default, in Templates, instead of checkboxes - I tried to specify Select Option, but the r