You could place your vote for this feature here.
That said, I’ve been requesting this since 2016. I’ve lost all hope it will ever happen. The closest thing Roon has done is to allow a ROONTRACKTAG to be added (via 3rd party tag editor, I use mp3tag) to the track file meta data.
I’ve done this so that I can sort/play tracks by genre, but it was quite a bit of work. Also, in some cases, Roon doesn’t like it if you use the same genre name in ROONTRACKTAG as is listed in Roon’s genres. For example, if I use the ROONTRACKTAG Pop/Rock, Classical, or Chrismas, Roon gets confused and won’t display them properly. In my case, I used Pop Rock (no forward slash), Classical_, and Christmas_ (note the underscore at the end) to get around this issue.
Roon is album based and has stuck to its guns on this, for better or worse (worse, IMHO). At this point, it will be a miracle if we ever get this.