Luffy & Zoro feel like the only true conquers when I think of what a CoC user should be. For Ussop it feels like the end of a character journey. I don’t feel that way with Sanji, I’m fine with him just being a really strong cook who isn’t driven by ambition like Luffy & Zoro, nor is it tied to his dream like Ussop.
Sanji might get it with some of the hints it feels like we’re picking up recently but imo it’s not necessary. Even the argument of him being royalty doesn’t work for me because Sanji wants no part of being a ruler.