I don't think so...
Just because Sanji isn't getting the same treatment as Zoro doesn't mean that he's being left behind...
We have to remember that Zoro's end game is far different from Sanji's... Like Luffy, Zoro's end game concerns being "the best"... Sanji's role and dream is more of a profession thing (similar to Chopper's whom we don't see fighting that much as well nowadays)... It's not fair to compare Sanji's development based from Zoro's...
Besides, Oda is just reminding us that Luffy and Zoro really are on another level and now that Jinbe is here, Sanji will most likely be on his level, if we base it on how Oda portrayed Sanji and Jinbe so far...
We are at Wano, the parallel of Roger and Oden, the significance of the Dawn (Joy Boy?) and the Hero (Ryuma), are likely being pushed to Luffy and Zoro...
But that doesn't mean that Sanji and Jinbe are left behind... I believe they are set up to fight King and Queen... It's just that Marco needs to do the role that Black Maria and Who's Who are doing right now...
No SHs should be left behind in this arc... Sanji is fine, no need to worry about him... If we have to worry, it has to be about Robin and Chopper...