I have two rabbits in the backyard, they are healthy and the enclosure is secure. (See this question)
How should I shape their surrounding to offer them good life quality?
Some facts that will make your rabbits place (outdoor or indoor) better for rabbits behavior:
One for most rabbits healthy behavior is to dig. Especially females in nature have the aim to build room for their children. If there is no place with soft ground they could manage to dig on solid ground. This could aim in hurted and maybe bleeding feets.
Rabbits love to literaly overlook their space. So some floors in different highs are welcome. For example my male runs up to the top floor if I come near, so he can look me in the eyes almost. Jump up and down should be save (no slipping ground, barriers will be noticed and included)
Almost for every rabbit in the group you can add a hiding place. Sometimes usable against predators, sometimes useful against intrusively companions.
For example with wood flakes or straw to dive into and stay warmth. Or simulate a nest like place.
In general different grounds to discover and choose (Cool stone plate, wood and other rough material to cultivate the nails and so on.)
It is not a mistake to change the "furnishing" sometimes (same things other place or new things same place) against boredom.
Racecourse / speedway
But after all there have to be enough free space for the rabbits to speed up and zig zagging!