WARNING: The following contains spoilers for One Piece Chapter #1023, "Spitting Image," by Eiichiro Oda, Stephen Paul and Vanessa Satone, available in English via Manga Plus and Viz Media.
In Chapter #1023 of One Piece, Zoro notices Sanji isn't fighting like his usual self. The chef explains that ever since he put on his "Raid Suit," his body has felt strange and off, though not in a bad way. It's been a long time since the Raid Suit was introduced and last mentioned, so this new wrinkle in its working might fall through the cracks of an already jam-packed arc. But the Raid Suit can do a lot more than make Sanji's body feel weird.
The Raid Suit is essentially technologically advanced clothing designed for combat situations, not unlike what the Power Rangers wear. Each member of the Vinsmoke Family has their own suit designed for their specific fighting skills and needs, courtesy of Judge Vinsmoke himself. When not in use, the suits are stored in canisters marked with the owner's designated number, with Sanji's being marked "3."
Once activated, the suit morphs and conforms itself to the shape of the wearer's body. The suits can only be activated by their designated user, and no one else. The suits enhance the wearer's fighting abilities, are fire-resistant, strengthen the power of kick-based attacks and have hover boots. The capes are bullet-proof, and Sanji's cape specifically can create a shield, though in the anime all of the capes are capable of this.
Each suit also has unique abilities. For example, Reiju's suit enhances her poison abilities, Ichiji's gauntlets create small blasts of energy and Sanji's allows him to become invisible. Sanji also plans to have Franky and Usopp modify the design of his suit to better fit his style, and to most likely distance himself further from his militaristic family.
What isn't known, however, is the effect the suit has on the wearer. In battle against Queen and King in Wano, Sanji says something is off with his body, though what he means isn't exactly clear. He says it isn't a bad feeling, just weird. It could be that it's a side effect of prolonged use of the suit. His siblings have all adapted to using their Raid Suits, but since Sanji's only recently started using his, his body may not have acclimated to its effects. How this will affect him in the long term also isn't clear, but hopefully, it isn't something more serious that needs worrying about.
