Thats not how it works? Just because Sanji doesn’t come in contact with his COMBO ATTACKS, doesn’t mean that his heat is somehow less potent?
Sanji fights outside of combos all the time. Look at his fight with Jabra, Oars, Pacifista, Queen (until the end), Page One, Vergo, or literally just anybody.
Fighting in combos is just one of Sanji’s many ways of combat. Using Sanji not melting Queen with Ifrit Jambe to discredit his heat is disingenuous, as he was using a combo in that instance. His heat is just there, but he didn’t rely on his heat to beat Queen.