I would definitely place some fun hidey-houses around. Ramps to run up and down might be fun too! I also recommend tunnels, and lots and lots of toys.

Give it as much freedom as possible. Rabbits need to have the space to run, jump and play. If you must cage the rabbit, make the cage as large as possible and plan for as much time out as you can allow. As long as the rabbit has something hard to chew on to keep its teeth from overgrowth, and anything it can nudge, toss or dig at is desirable.

So cool that you can have a space dedicated to your pets!! I would recommend having a hidden house, litter box (multiple if you have more than one bunny), of coarse a bunch of toys to keep them occupied, maybe a basket (with uncured wood) with hay in it as a snack bar, tunnels, and cardboard boxes. Its always good to have plenty of toys that you can switch out so your bunny doesnt get bored. Don’t forget to bunny proof the room so any exposed wires should be covered. any spaces that the bunny likes to dig or pull at the carpet you could put a Timothy hay mat in place of it. My bunny is free roam in my room but I have an X pen setup for her with her litter box and food just in case I have little cousins around or when I am going to be gone for a few days and someone needs to take care of her. To help them feel more comfortable you can take something of theres from there previous set up and put it in the new room. Good luck on your new space!!!