Back in whole cake sanji before any new upgrades was comparable if not the strongest Vinsmoke. In onigashima sanji got an exoskeleton making his body significantly more powerful increasing his overall stats
Unlike his siblings a one of the many advantages he has over them is haki something they usually would make up for with science. Because sanji has haki tho he’s able to stack it on top of the Vinsmoke upgrades to make them even greater just like he did in onigashima
Against queen he stacked his armament haki on top of the toughness of the exoskeleton making him even more durable and able to handle hotter flames
I think it might become a pattern
Imo I still think sanji will likely fight laffitte of the bbp and improve his observation haki. Maybe when the exoskeleton is activated it boost not just the physical body but the senses as well. Like boosting ones like sight smell and hearing. So when sanji stacks his observation haki onto it it’ll further make him stronger
His final power up potentially being a new raid suit made franky usopp and vegapunk. It again further strengthening his body
It’ll also specifically be made to enhance or highlight his fire powers just like the other Vinsmoke kids suits are made to enhance their own abilities. Adding again to his durability and senses that Sanji again could stack his haki with
