Funny, 30% is also about how much larger the Yamato was than the Iowa class. But it turned out larger battleships weren't the deciding factor that time. Who knows whether larger carriers will matter for winning the next war?
Each US Supercarrier has two runways and four catapults. That's why they weigh so much.
Tonnage isn't the only factor. But presumably, having two runways on one carrier is a key advantage in carrier based combat. If you can launch aircraft faster than the opponent, you'll get more aircraft in the air before they can.
Can China's 3x aircraft carriers launch as many airplanes as one of our supercarriers? How many Chinese aircraft need to launch to have a chance against an F35C?
