We took ours to Majorca at exactly the same ages.
It was great! Yes, not like before but still fun.
Definitely take a buggy, umbrella fold that you can take all the way to the gate and go through the fast lane at airport security.
Don’t make heaps of plans. We had two “poorly” days where our girls ended up just relaxing in the room/balcony. If you have iPads/phones maybe pre-download a few of their favourite shows just in case.
Make up two bags of new, cheap toys/crayons/snacks etc. - one for the journey out, one for the return.
Cheap UV tent off Amazon for the beach/pool, complete with cheap paddling pool inside.
Hand sanitiser he l is really handy to get greasy sun cream off your hands (you’ll be applying it a lot!)
For the journey, if you can I’d really recommend getting extra leg room seats. Ours just sat on the floor after take off playing with toys. Various other (CF!) parents were wandering up and down the aisles with their toddlers and stopping “for a chat” (so their kids could play in our space).
The issue I didn’t expect was sand in the children’s eyes. Mixed with salt water and sun cream it was a very bad combination! Invest in some goggles.
Relax and go with the flow. Enjoy!