Yamato is the daughter of a Yonko and refuses to become the new Shogun of Wano. She doesn't want to be the queen of anything. Ace didn't want to be a king, Oden didn't want to be a king, Shanks doesn't want to be a king, Katakuri doesn't want to be a king, Sengoku doesn't want to be a king, Whitebeard didn't want to be a king.
And CoC has noting to do with a desire to be a royalty either, you think Luffy or anyone else I listed above cares about that ? Besides, Sanji didn't leave his life to become a cook, Judge disowned him and he had to flee to live a decent life.
All CoC users have superhuman pride and won't not back down on anything something which is the complete opposite of Sanji, they also have a dream in which they will never give up on no matter what, again something completely different to Sanji who has abandoned his dream and has told others to do the same because its impossible achieve ones dream, Sanji has as much chance of getting CoC as Chopper does.
Also let me quickly correct you on a few things:
1. Yamato felt pride in being a samurai of Wano and wants to protect the nation, she never gave it up even after 20 years of abuse from Kaido;
2. Ace wanted to forge his own legacy and have his name reach every corner of the world as a great pirate, even with all the hate from being Roger's son Ace still wanted to be more famous than Roger.
3. Oden wanted to be free to do what he wanted, to not be told what to do by anyone, even after helping build Kuri he still went out to see and become free
4. You don't know what Shanks wants so saying he doesn't want to be king is your own headcanon, from what we have seen of him though Shanks just wants to see the world and not be held back by anyone, a sort of freedom if you would.
5. Katakuri wanted to protect his siblings, he even told himself he would never lose so that everyone would fear hurting his siblings
6. We don't know a lot about Sengoku but his pride in justice was second to none, he had extreme pride in his values of justice and never back down from them
7. Whitebeard wanted to have a family and protect them no matter what, he even protected his home island and stopped all the war there and gave them peace, not once did he abandon those he viewed as family.
Sanji has given up his dream because it was impossible for him, he didn't have pride in himself nor the determination to even try, but just like Bellamy him meeting Luffy and Zoro changed this for him as he saw them rather die than back down to anything or anyone, this level of pride is something Sanji still doesn't have as he would rather leave a life of servitude and abandon everything just because the road ahead is tough. Oda has written Sanji as a more relatable character, and multiple people have commented on how much of a kind man he is, he would rather leave a life of servitude than try and trample on others, and for this very fact Sanji cant get CoC because he would never trample on others.