Another scenario I'd like is Sanji taking Queen (so a slightly wealer opponent) but coming in a clutch Enies Lobby-Mr Prince style at end of the war, by kicking Big Mama Chanter down the waterfall when they are approaching Onigashima for the 3rd time.
This way he would parallel Marco-King being the 3rd flying fighter to do this and will be a payback for everything that happened in WCI
A sort of "It wasn't a pleasure, bye bye"
I mentioned this in another thread but don't remember which one
If he soloes a calamity then the calamities are weak as fuck, I mean he's been weakened quite a lot now while King and Queen have been chilling most of the time.
Only Jack put on some work but I doubt Sanji will fight him.
It's more likely he would go for Queen or maybe (but I doubt it) King. In any case, it would make the calamities look bad. Not that they look any good rn.