Cost of keeping different sized rabbit?

My 2 buns and I are going to an adoption dating event looking for a third. One is a gentle giant who is supposed to be very docile with others.

If the bunnies like each other, I have a question. This rabbit is three times the size of mine. Will she eat three times as much? Use three times as much litter? How does that work? Is a spotted giant more delicate medically than small lops?