I’ve literally just got back from travelling to Hong Kong and Shanghai with a toddler and a 4 month old today!
Things I found helpful we’re pre-reserving the sky cot/bassinet phone up the airline and request one and they’ll make one of the bulkhead seats hers as that where they attach the bassinet. It has to be stowed for take off and landing though so for this my carrier came in SO useful it meant I had two hands free to wrangle the toddler that was trying to claw her ears off and slide out of her seat for all of the take off/landing.
Check the buggy and use it until you get to the plane gate, you will have to make it beyond clear about a million times that you need it at each gate especially if there is connections if not it’s usually fairly easier, a lot of airports have buggies you can use for around £1 or free failing that when the biggie went missing after our first flight to Shanghai I just pushed the toddler around in a small luggage trolley 🤣
LOTS of snacks/juice/milk for the toddler mine wouldn’t touch plane food nor would she entertain their juice she just wanted milk which I got plenty of in the airport.
One thing I found the absolute best travel item was one of those inflatable footstool/toddler bed type things. It’s like a big square that you blow up and put in front of the plane seat so it turns into a little bed for them. There’s loads on amazon prime cost me around £10 I think. My daughter slept all but two hours of an 12 hour flight because of this!!
Utilise other people! Whenever one of them cried staff couldn’t do enough to help me, ensuring I ate and drank enough and other passengers were very kind and understanding of crying, the man I was sat next too fanned the baby for an hour straight because he was too hot and grizzly. Lots of people helped me carry things, or on and off the plane and bus safely. Don’t be afraid to ask for help.
Calpol too, I took a bottle in my hand luggage to try and prevent hurting ears. Gave a dose about 30 mins before the flights and landing which seemed to help slightly.
Hope that helps!