Very possible but there's always the chance his last major fight is Aramaki. I think Saint Shepherd Ju Peter is a possibility.
Sanji got overwhelmed quite effortless by Saturn but I don't think anyone expect him to randomly jump to that level. This is the final saga but there's still plenty of factions for the crew to face for Sanji to grow. His Blackbeard Pirate opponent (I feel like it'll be Avalo Pizarro), his Admiral opponent (Aramaki fits quite well) then finally Saint Ju Peter. This is assuming all the slots aren't full and these enemies will be faced at different times. Him stopping at Aramaki wouldn't be too crazy or disappointing but I feel like Sanji facing a Gorosei isn't wild either when there's 5 of them.
Overall, Sanji grew quite a lot during Wano, I wouldn't be surprised if he goes from getting handled effortlessly to beating one over the course of the final saga.
Sanji got overwhelmed quite effortless by Saturn but I don't think anyone expect him to randomly jump to that level. This is the final saga but there's still plenty of factions for the crew to face for Sanji to grow. His Blackbeard Pirate opponent (I feel like it'll be Avalo Pizarro), his Admiral opponent (Aramaki fits quite well) then finally Saint Ju Peter. This is assuming all the slots aren't full and these enemies will be faced at different times. Him stopping at Aramaki wouldn't be too crazy or disappointing but I feel like Sanji facing a Gorosei isn't wild either when there's 5 of them.
Overall, Sanji grew quite a lot during Wano, I wouldn't be surprised if he goes from getting handled effortlessly to beating one over the course of the final saga.