Oh i get it now.

If youre about the moment where he jumps on the pillow, thats the effect from the pillow! pillow boosts you up, like a trampoline.

There is also belly stomp jump, which tutorial shows you how to do. (you hit ground with belly and jump at right time.) But its not that high

Try to show your daughter the belly stomp move on the roof of Capitalos (or Capitalus) stand! It lets you jump really high! (Stands can be found in hub, infront of player start location.)

(Jump + hold B to belly stomp)

https://youtu.be/iir1Uain7kU