How much room are we talking? Ideally, it would be as big as you can fit in your space. But, if she's like mine, and free-roamed during the day, and their cages are their "houses", there's a lot of conflicting opinions, but she should be able hop around freely, stand on her hind legs without touching the top, and have plenty of room for hay, toys, water bowl, food bowl, etc...
My Lucas has a house that's made out of three large dog crates. I like them because the sides can be taken off and they can be put together with simple clips, and the bottoms have trays, so he's not walking on wires. He also has several rugs and towels, as flooring, and only has an exposed bit for flops!
He house may be too big for a free-roam-able rabbit, because he often opts to stay in it rather than coming out to play!
https://bunnylady.com/set-up-a-rabbit-enclosure/