Sanji didn't defeat drake.
Having his eyes white and being knocked to the ground isn't a sign of defeat, especially not for zoans who have ridiculously tough endurance. Kaido's eyes also went white when luffy used elephant gun, was he KO'd?
You can say Sanji> Drake, but I doubt the gap is this high. Sanji would need the raid suit to do it, otherwise that would imply Page One> Drake, which we know isn't true.