Rei and Claire's combined magic will lead to a Yuritopia. But yes, Rei's submissive nature and Claire's dominance even extends to recessive traits like eye color and hair. Eventually the kingdom will be renamed the Land of Gaybies.
Edit: My apologies to the commenter below, I didn't think to include a link. Here is the first chapter I posted, not the first chapter of the overall story, but the one that includes a scene that I believe would look similar to this pic. https://archiveofourown.org/works/27643132/chapters/67636831
Oh, Morgan was a blessed with the fact they make adjust her for Gudako lines, she is the second female servant who use the word wife to another woman in the game ( first is Altera mentioned her wife once)
Still, a lot were waiting she was bonded to Artoria thanks to Yorukun drawns