I am late to the party, but an item I haven’t seen is: prepare the kid.

We have flown a bunch of times with our kids. The days before departure, there are “drills”: lengthy explanations of what will happen, getting the kid curious, answering their questions, reading stories of kids traveling. It means that, once we get there, the bulk of the experience is not fully unexpected, so the kid doesn’t freak out.

We never had massive tantrums while traveling, only standard hungry/tired cries we usually managed in a couple of minutes, with any bribe that would work.