First two years they can fly for free, but they have to ride in an adult’s lap and that gets tiring. Don’t believe the bassinet offerings - as soon as a plane gets turbulence, you have to get the sleeping baby out of the wall bassinet and good luck appeasing them. Age 1-2 is hardest for travel, so you can skip it. The only thing that worked was getting their own seat with the cosco scenera next car seat (or their own if they like it, but that one is $50 and light to carry). They would sleep nicely for large chunks and you get to enjoy travel again. After age 3 it’s much easier (they can ipad if that’s the only ipad time they ever get).

Don't go straight to screens in this situation. You can introduce novelty by purchasing a number of cheap toys, even from the dollar store, which they have never seen before. Keep them hidden until the flight.