I had couple 🛫 from UK to Europe when our baby was 8 Months and 15months. Last time I really struggled as my lady wanted to run everywhere in the airport and didn't wanted to sit in the seat. Needed lots of snacks, new activities
My carry on was full of toys and it really helped. Toddlers do like playing with the airplane window, so use it. We booked the front two seats on sunwing with extra legroom, which really helped. We had the little man trapped in front of us for the 7 hours ride. We made a point of not walking him around on the airplane but that only worked bcz it was reasonably short plane ride. Getting him to nap was difficult…but obviously try your best. The vacation to DR was well worth it!!
I haven't done lengthy OS trips as yet, thank COVID, but I have flown interstate quite a few times with my son (2) and I found tiring him out at the airport and having his favourite toys to play with work really well, we usually fly around his bedtime so that he sleeps most of the flight.
Travelled to France for my sister's wedding when my son was almost 2 yrs old and my daughter was 7 months. Choose your flights to fit their sleep routine, if it's the first holiday try short flights, pick accommodation that caters for the kids and try and get time to relax. It's your holiday too. I've also been to Turkey when my son was almost 3 and my daughter was 2. The hotel had a creche and a spa. It was amazing. There's a company that deal in toddler friendly holidays. https://www.kiddieholidays.co.uk/30-amazing-all-inclusive-toddler-friendly-hotels-in-europe/
We took our two year old and two month old to Serbia and I was so anxious about it, but they both did great! We took playdough, coloring books, finger puppets and suckers. It kept our two year old busy the whole time.