Contradictory much!
so Sanji will be there because monster trio but he’ll be leagues behind Zoro?!
far our forget your wife, mate you might need an actual head doctor?!
If Sanji doesn't awaken ACoC, then yes, he will be
significantly weaker than Zoro EoS just as he is now. Name one character who is mid top-tier or stronger without either ACoC or a top-tier DF.
Kuzan showed that it is possible to match a low top-tier without using a top-tier ability or ACoC, simply by having strong physical prowess, strong haki and an ability which augments that. The version of Kuzan that barely used his fruit against Garp was literally EoS Sanji. His Ice Glove was like DJ/IJ and managed to bridge the gap in AP between one who doesn't have ACoC and one who does.
But that was an old version of Garp who was significantly weaker than his prime by his own admission, multiple times. That same version of Kuzan would have stood no chance against a prime Garp and would have been forced to use his top-tier DF abilities. The only way to counter powerful ACoC is with a top-tier ability and vice-versa, so based on what we know in the manga thus far, unless Sanji either eats a top-tier DF or awakens ACoC, he will never be on neither Luffy nor Zoro's level again.