King didn't break the hull of the Big Mom Chanter (which should be much harder naturally) But Sanji's roundhouse kick (with no massive amounts of momentum like King used) midair redirects the giant sized cannon ball (it is held together by Caesar into essentally one big cannon ball) creates an impact that imparts significant damage to the starboard side form the impact of his launching the cannon balls with the force of his attack, like you can fit x number of Thousand Sunnies in the crater created
The BMP stop pursuing the strawhats after this attack from Sanji
King in full zoan vs Sanji with the impact of DJ midair with no momentum, stops and redirects the cannon ball that destroys the starboard side and the ship incurs siginifcant structural damge
DJ Sanji did fucking more damage than King
But today in the International tea day. I drink the tears and salt of Sanji, of his haters and fans alike, it tastes good.