Those would be linear or probably slightly less than linear costs though.

More people in a house eat more food, but you can buy in bulk for savings so cost per person could go down.

Utilities would scale more or less linearly given the area of the house stays the same. Water is iffy it might go up with more people having showers but might go down by doing larger washing loads at a time.

Transportation is interesting though as it's theorized cars having 5 seats caused a tiny effect on families only having 2 children because there's not enough room for 3 baby seats in the back of most cars.