What's this nonsense about Sanji getting KO'ed ?
He's not shown laying there on the ground, and then later on getting up.
He's not shown with white eyes like Luffy was when Zoro ran around with him.
He does not hold his head in pain being confused about what happened to him.
As i said in the Spoilers Thread, the outcome ended up being that King Failed his attempt to pierce Sanji with his beak, and whatever damage Sanji might have taken to the targeted area, in this case his stomach, it's minimal since there's no attention drawn to it, and the focus continues to be the durability of the RS.
He only has one of his cheeks slightly scuffed after crashing at high speed from high up, while posing with no discomfort alongside the other SH's
But that's arguably less then what happened to Denjiro or Ashura
When dropping at high speed from a high place.
At the end of the day this whole encounter served to hype RS Sanji while up against a Yonko First Mate.