Folks make a valid point on it being unlikely that Oda is familiar with the term "CoC" but at the same time, you never know, could be that Oda stumbled on that term somehow. Don't know how valid it is but I've heard Oda watches some Japanese YouTubers so why not English YouTubers as well?
On the wording itself, I don't think it is a mistake or misspelt as that'd be inferring Oda doesn't know how to to spell "cooking" in English which is rubbish imo so it's most likely intentional. You can also see the name on the side and front of the book so it's unlikely Oda jobbed on writing an "O" twice. It's clearly a C. Only argument you could really make here is that Oda wrote the word "Cocking" which doesn't really mean anything and the addition of the crown at the end even makes less sense in that case. Not sure how Oda stumbled on the phrase but I really do think think Oda's intention here is "CoC King" with the crown being the most telling indication of it. Considering how much Oda loves using puns I reckon the phrase "CoC King" here is a pun on the word "Cooking" hence why there is no space inbetween.
Anyways it's a fun observation :p
Personally I do think Sanji's qualified to have CoC and I can't speak for anyone else but I honestly don't really care if Oda gives it to him or not as Sanji's strength will always develop relative to the rest of the M3 regardless. It's hilarious however how convinced some fans are that he will not get it tho, didn't know you lot were the ones writing ONE PIECE
but carry on lol, will be funny to see the how you backtrack from this if he does get it.