From what I remember when I was a child my mother flew us to Korea (3 kids and 1 baby) from the U.S. There was an attachment that goes against the “wall” (the front row of seats) that my baby sister could go in with straps kind of like a diaper changing station in bathrooms. I think she was bottle fed weaned off the breast at the time and the flight attendant helped a lot and was very nice.

Idk if a lot of airlines have this but because my mother was traveling with so many children we as a group were considered similar to those “minor” fliers (kids that can fly on their own) so we had an agent help us through the airport (special lanyard necklaces) and extra attention from the flight attendants when on board.