Traveling with 2 toddlers on an international flight.

I have 2 girls . 1 year old and 2 years old.

I’m going to my country and the overall travel time is 21 hours.

We will fly from nyc to Istanbul which is roughly a 9.5 hour flight. With a 5 hour layover in Istanbul and a 6 hr connected flight to my country.

If anyone has traveled with 2 or more kids in a really long flight, can you please advise me as to what I should do. I don’t my kids to be the “annoying” ones crying the whole time. I know people get frustrated because they’re tired, but they need to understand kids cry. But how can I keep them busy and feeling good, not irritated, until we reach our destination?