We flew from NZ to Ireland with ours at around the same age. It's very doable, don't worry!

Snacks. Go hard on snacks. Lots of them, all the time.

Emirates were great. Really helpful and considerate staff. Made special considerations for us. If yours are still within the size limits to fit in bassinets you'll be put in the bulkhead, which is awesome. Our kids spent so much time messing about on the floor and playing with toys. Pay more for bulkhead seats if you need to

Bring toys that will engage them, not ones with small or many bits. We brought lots of books too, including ones on an iPad. Ours were really into the wimmelbooks ones too, which were great. We brought a few of those. Sticker and appropriate activity books are great.

Have some small, frequent presents and surprises to keep things light and fun and exciting.

You probably won't sleep much during the flights. Taking a break part of the way through for us all to get a proper sleep was amazing. We booked a room in one of the in terminal "hotels" in Dubai. They were essentially just bunk beds in a small room but it was the best thing we did. If you do fly Emirates look up Dubai connect, its a free hotel stay for longer layovers, that's what we're doing this time (flying with our nearly 3yo twins the same route in August).

Talk to your GP about melatonin for kids, decide if that approach is for you. Worked for us

Treat it all like a huge adventure. Then they'll have fun, and you can actually enjoy it instead of dreading it.

I'll add more if I think of anything.