Thats what EtenBoby implied on her translation
This one makes 0 sense because Oda is basically contradicting himself in the same sentence.
"Sanji was born as a normal human (implied 2x)" ----> "He ONLY awakened the science in his body through the raid suit during his fight
----> "Sanji already had that fire resistance in the past thanks to his alterations"
Like... Is Oda going senile already?
Completely nonsense translation. Thats why i also thought he could be talking about the Raid Suit, but now Eten's translation summed it up