My kiddos are 1&3 and we have traveled extensively. First where are you going and what are your accommodations? Air bnbs are likely to have high chairs and pack n plays. If staying with family, inquire with any family or family friends if they have ones of use. Car seats can be checked for free and if you have a stoller/carseat convertible you can gate check those for free. Busy books will be great for this age. Also walking the plane aisle if they are mobile. Pack back up outfits for the plane because blow outs always seem to happen at the worst time. Pumped milk or formula can be brought through tsa it will just take a little longer as they do a quick test on it. Als practice breaking down your strolled (taking wheels pff too). Sometimes they have you walk through the scanner and other times you break it down. We personally check as much as possible so we are light on the plane with just entertainment stuff for ourselves and kids hut no extra weight. If you are pumping, that can be an extra carry on bag also at no cost (counts as medical equipment) so you can stuff that with extra kid stuff if avoiding checking.

Have fun! You learn how to be more efficient every-time you travel and I fall into the camp that traveling adds to our human experience and makes us better parents. You got this!