There are good bits and bad bits.
Holidays are far more. Its harder to find rooms for five, where as rooms for four are quite common.
Holiday deals and free child places are often one per adult.
Things like swimming its one swimmer per non swimmer not in arm bands.
We went to a seven seater because three across the back didn't work for us.
Grandparents didn't feel they could cope babysitting three DC.
I found myself with three children at three educational settings all finishing at the same time. That was very expensive and a logistics headache.
Mine have all ended up needing their own rooms DS1 17 autistic so needs own space, DS2 14, DD 9 social communication issues so own space required and half sibbling of 14 year old DS so sharing not a consideration.
On the flipside...
Going from one to two children is a big change but I found two to three a breeze.
I love my brood, I love leisurely family meals, that each of my DC is very individual, that love grows with each child.