R.S.
I let my kid take the cushions off and jump on the coach. Really, there is no harm in him doing it and it helps him exercise. Jumping also feels good from a sensory perspective too. If it bothers you, get him something else to jump on.
It's my observation that it's still hard to understand cause and effect/consequences at this age.
If I'm gentle and firm, my son obeys. If I get ticked off, he isn't as compliant.