Completely depends on the rabbits
Some will chew everything and anything and enjoy destruction, some wont touch much but go nuts for certain things, some will just nom wires and thats it, and a very small minority wont damage anything.
How easy bunny proofing is depends on how destructive the rabbits are and how much you are prepared to build the room(s) around them. Some rabbits will ruin any house, and need every single wall and piece of furniture to be protected by a mesh barrier - some will just need wires tucking out of sight. You sort of have to design the room around the bunnies rather than the other way round.
Generally, with my buns, I remove all expensive and non-essential electrics from the room (they only had access to one when unsupervised) and accept that those that remain will need the wires replacing every now and again. I bunny-proof these wires by moving furniture around to put the wires behind, and bunnyproofing with mesh NIC panels. I make sure there are no loose or frayed bits of carpet or wallpaper. I try to remove any real wood furniture and accept that those bits that remain may be nibbled. I move furniture to make sure that there are no dark corners or ways for rabbits to get underneath furniture - I find that these are the places that they get most destructive, perhaps because it is out of sight but I do wonder whether these shadowy areas that are used as 'hidey holes' trigger the instinct for nesting and digging a burrow. I accept any fabrics within reach may get holes in, or occasionally weed on, so keep those to a minimum. That's about it
My two are really quite good with not being destructive, they just need it keeping on top of, if they show interest in destroying a certain area of carpet or furniture then it is blocked off, hopefully before it becomes an obsession.
eta- someone mentioned hay - yes! it gets EVERYWHERE! My buns are outside now, and one of the main benefits is that my clothes and bed are hay-free now. I would still rather that they were indoors though, its much easier to spend more time with them, and I had a better relationship with them when they were indoors.