The best advice is to try to get the child to sleep. That said, Murphy’s law will dictate that about 2 seconds into the flight, the kid will be 100% awake and bouncing until landing, at which point he’ll prove that inert matter isn’t movable. The bottle or something to suck on on descent is critical - and handy advice for us adults too.
I used to fly often on business, and never minded kids on the plane myself. It can be really rough, though, if you don’t have a separate seat for him and the plane is full (not to mention dangerous, since he can’t be belted in, in the case of sudden drops). [Not to mention awkward with food service - which is bad enough for space]
Good luck!