Uncrowned king is perfect tbh
Sanji being forced to use his kingly traits to eventually dethrone Judge's legacy and set a new meaning to Germa's existence in the future, to fulfil his ideals of world like not letting anyone starve. After making Luffy king of course, but as Gaban said, he needs to be a king to make Luffy the king. Zoro wants to be king, not only to honor Kuina and his own promise, but to honor Luffy's at the same time.
Having the good side of his origins in mind (Sora, Reiju and Colette), he needs to make justice for them and honor them.
Luffy also states he doesn't want to rule anything like a king usually does, he wants to be the most free, so it could work the same way for Sanji. His self depreciation due to what he went through and his despise for royalty and its deeds, or whatever that is, needs to be replaced by self promotion to honor the people that cheer for him and give a whole new meaning to his origins instead of merely running from any association with it.
I said it before and i will say it again: Shanks and Sanji are showing to be very similar.
Shanks isn't running from the responsability that he carries, he knows what his family is capable of, he knows his origins and knows what they aim for, but he isn't running from it, he wants to give it a new meaning.
Shanks once said he just wanted to be a "carefree pirate with Buggy", but something had to change
A real king doesn’t run from his responsabilities, he either embraces it or gives his best to come out at the top of it.
That said, uncrowned king sounds badass..