These were introductory arcs
Every time Luffy's crew fights an enemy organization, Sanji has a solid 1vs1.
Arlong pirates
Baroque Works
CP9
Beast Pirates
The WG is supposed to be Luffy's biggest enemy organization, which has been fighting a battle for 800 years, it is obvious that one of Luffy's wings will have a confrontation against the pillars of the WG organization, this shouldn't even be a discussion
Nothing about introductory arcs, they are their own arcs, some tremendously long like Dressrosa or SP and Sanji simply did not fight with a rival similar to Zoro and on many occasions we have seen Zoro fight against higher levels, while Sanji did not or with very poor performance . The facts are the facts. It has happened and it may happen again, or not who knows.
As for the WG, we don't know who will end up as an enemy and who will end up as an ally, so it is normal to have doubts, there will be too many actors in action.
The Gorosei at the moment seems to have CoC and Sanji doesn't, that could make him fight against Kizaru, for example. Quite early combat.
As for the Gorosei, we could have Zoro, who is also a figure destined to surpass even Ryuma, Yamato, Dragon, Sabo?, Shanks?, Boa Hancock? Law? Garp?...
It is likely that the Muguiwarar will not be the ones to defeat the Gorosei, especially since perhaps Sanji and Jimbe can justify themselves, but the rest cannot.