King: Flys, uses fire, and clashed with Sanji
Zolokeks: bu buh He HaVe SwOrD
Queen sent the Tobi Roppo after Sanji earlier in the arc
Very Quirky like a majority of the opponents Sanjis defeated throughout the series.
And seemingly has knowledge of Vinsmoke Judge....
While Sanji and King seemingly have some similarities in terms of how they fight, that typically only amounts to just a clash not an actual fight, and its
generally not in Sanjis best interest to go up against someone like that. Doflamingo and Vergo both had some of Sanjis abilities, that's why Sanji struggled so much against them.
Plus Sanjis never defeated someone of King's character archetype really