My partner’s friend (25F) socially changed her name from the name her mom gave her, to a name she chose for herself. She is cisgender, btw. Her name change is due to her wanting to reinvent herself. And her new name, Queen, reflects how she thinks of herself and how she wants others to see her. Her social media usernames and profiles reflect her new name, and people she’s met in the past few years call her by the name she’s introduced herself as. I’d be glad to support her in the autonomy she seeks by naming herself. But my issue is that she wants everyone to call her Queen. Within the friend group I notice that sometimes her old friends slip up and call her by her given name. But you can see that it doesn’t sit well with her, and that being deadnamed, bothers her. Sometimes she’ll politely correct, but not within larger groups. Sometimes her friends self-correct and call her Queen.

Since, “Queen” and “King” are used as terms of praise, reverence, and endearment, I am very hesitant to call this person “Queen”. I simply don’t feel that way about her. That says, if she tells a funny joke, or I’m fondly greeting her, it’s easy to call her Queen. It just doesn’t feel like a name to me. It feels more like a title. I don’t feel right calling my peer Queen. If she were to change her name to a name that means queen, like Reina, I wouldn’t experience any unease with calling her such.
I avoid using any name to refer to her. If I do use a name, I try to say Queen but if I’m not in a good mood or if I’m annoyed with her, I don’t bring myself to say it. I asked if I can call her “Q” and she said no, my name is ‘Queen’.
Perhaps I would feel differently if it were a stage name.
Edit: In the original post, I referred to the person as a “friend”. More accurately, they are my partner’s friend. I do appreciate the replies that address how a friend should treat a friend in this situation.