Sanji vs Jack would be a complete mismatch.
Lol why ? He's agile enough to not get hit I feel like Jack is the weakest calamity for 2 reasons
1 he's the first one shown
2 he's so one dimensional because his fruit just turns him into big mamoth ... I mean so yeah I feel like Sanji would fight jack
Zoro would fight second strongest calamity and either luffy and law take on strongest or law takes on strongest while luffy goes after kaido problem is neither luffy zoro law or Sanji proved to be able to handle someone on jacks level alone (luffy has power capacity but can't out right beat them especially if someone has high durability and I can only guess Jack is a tank due to his fruit perhaps even more so then doffy but he prob cannot tank gamma knife)
Jacks hype puts him at doffy level
It required both luffy and law (not only to use ultimate attacks) but team up to defeat him
So if the powerscaling stays true zoro and Sanji may have to team up to fight jack
And luffy and law for the other or luffy and law gets strong from fighting at dress rosa and able to take on one calamity specifically while zoro and Sanji due to not having feats or strong people that they fought and showed good showing against will team up
Lastly if anyone in this alliance can fight Jack it be Sanji I say this one because of his speed this would also be perfect time to show off observation haki etc not to mention he fights with poison as wel something Sanji can fly out of the way we seen luffy go against poison before (both Caesar and the jail guy) he may be resistant to it but idk
Sanji just needs to show he can put out damage but he would have best chances if going on sole ability against someone like Jack because of his mobility
Second would be law due to hax and gamma knife
While I'm sure zoro and luffy can fight Jack it will be annoying fight because he should be a tank so zoro and luffy fighting styles would take the longest to defeat a tanky char as zoro will just continuesly try to cut him down and luffy would prob just continuesly punch him till he would most likely need gear 4th or something