What are your best Airplane travel tips with a 2yr old and 6m old?

Question

Have a trip planned in a few weeks 4.5 hour flight each way - me, hubby, 2yr old and 6m old. 
What are your best kid travel tips??
What are good plane friendly activities?
Husband and I used to travel a lot, pre-kids, and have taken our March ‘19 baby on a few flights pre-covid but that was more than a year ago and he was a baby and would just fall asleep. And now we have another baby. So a bit nervous for traveling with 2 of them, one being a non-stop rambunctious toddler.
Also any Toddler mask wearing tips?  
We practice obviously but he chews on it and then doesn’t want to wear it. So I’ll bring spares... but nervous about it on the plane since I’ve heard they are very strict for 2yrs and up wearing mask while time.

Answer

6mo is the easy one. Nurse or have something to suck on for takeoff and landing, but basically that's the main prep.
For 2 it's harder. Sticker books, small figurines, a mini play dough or coloring pad can help. Offer one every 30-60 minutes. Lots of snacks, especially hearty snack like crackers with cheese or peanut butter, fruit, a little noodle pouch if the flight crew will let you warm it up. Buy some old school dum dums lollipops. A kid might even be able to suck it under a mask, and we got like 20 minutes of quiet time out of one of those bad boys.

Answer

We made the mistake of trying to force our daughter to stay in her seat. She just wanted to climb up and down/all around. Fortunately the plane was pretty empty so even though she was a lap infant she still got her own seat. 
Bring favorite snacks or books. We got a Maga doodle off Amazon and it was a big hit. We flew at night so she was in footie pjs and had her lovey with her. 
Try to stay calm and relaxed and I think they will feed off of that

Answer

Wear the baby through the airport, push a double stroller with your 2 year old. 
Lots of dollar store activities and tons of snacks. We got silly putty, sticker books, a dry erase board, coloring books and crayons, headphones for music or movie (depending on what your flight has to offer). 
Extra clothes for everyone. 
We always bring blankets for our kids too.
Brings large empty water bottles to fill up once you’re past security. You actually can probably bring them full since you’ll have the baby. You can also bring fruit/veggies pouches and things like that. 
Pack like things together. Ie Food in one bag. I always put it in a plastic bag in whatever travel bag I have it in. Sometimes security will make you take the food out, sometimes they won’t. But if it’s in a plastic bag it can stay in that bag opened and be easily put back into the travel bag instead of having to put 186364833736 back individually.