I think a feature that would be really cool would be the ability to set hair colors as a Hex Color Code or set it via RGB values when you have Operator permissions and are therefore able to use /mca-admin.

Additionally, I think this would be great to also have for use on a player at any point, no matter the permissions. Though, this is just my opinion, and you would need to use the Villager Editor item to do it to villagers.

I know there is the config option to have villagers spawn with custom hair, but there's no easy way to try to set the hair color you want, and once a villager has one of the special hair colors, it can't be changed.