We have four kids and have taken lots of different holidays.
When the kids were very small we tried to set up luggage/buggy etc so that one person managed two large wheelie bags (plus a large rucksack on one holiday!) plus travel documents, and the other person managed all of the kids. Kids over 4ish had a small backpack for the aeroplane which they carried themselves.
When travelling abroad with baby/toddler twins we found two single buggiesstrapped together to be the best combo. I bought some adapters to connect two umbrella strollers together, but actually Velcro straps connected them better. That way we could have single buggies or strap them to be a double buggy for airport/solo parent time. If the kids are small, make sure the strollers lie flat so the kids can sleep in them during the day and evening.
When abroad, we have stayed all inclusive (no cooking, minimal cleaning, minimal washing etc) and also taken our caravan. Both worked well, but were different levels of hard work!
We have never hired a car abroad since having kids. We have used busses, trains, ferries and trams!
Jet2Holidays have been brilliant for family rooms. Service always excellent, and rooms have always been exactly as described. We normally have a two-bed apartment; double bedroom, twin bedroom and two littlest on the sofa bed in the lounge. We would sit in our bedroom or on the balcony when the smalls were in bed (or go to sleep ourselves, more often).
I have taken the kids to AirBnBs by myself, and taken them camping in our caravan (many many times) and (once!) in a tent. Takes a bit more organisation than home+day out, but gets easy pretty quickly.
Don’t be put off travelling with lots of small kids; it really is fine. If you can manage a day out in the U.K. then you can manage a holiday abroad!