Welcome here!
The absolute minimum size is 2×4 feet, but you’ll quickly discover that this is not nearly big enough for a litter box, food dishes, hidey house, and toys. You can do multiple levels to add more space (people make “condos” out of wire storage grids) or you can get a dog exercise pen that is 4×4 feet.
I would recommend putting the bunny in a “family area” like the living room, dining room, or rec room. Even if it’s your “daughter’s” bunny, you will be the one responsible, so it’s best for the bun to be a family pet getting to interact with everyone.
Rabbits don’t like being picked up and carried, so house him/her in an area where the bun will be able to come in and out of the cage on his/her own.
Please do a lot of research on rabbits. Many people don’t realize that they require daily veggies that can get quite expensive and that vet care is not cheap. You can save money on spay/neutering if you adopt a rabbit from a rescue. They usually alter them prior to you bringing them home. An unaltered rabbit will be smelly, aggressive, and destructive, so it’s a must that they be spay/neutered.