This is a false belief. Bunnies actually need a kennel anywhere from 4+ times their size. They need to at the very least be able to hop 4 times in a row In a kennel. This kennel is only good for times when you are not there to supervise. They will need to be let out of this kennel to fully stretch their legs and run around (minimum of 2 hours a day). If a rabbit Is unable to hop around, they can experience health declines such as bladder sludge and depression. A great option for bunnies is an XPen or baby gate attached to their kennel. This allows them space to run around, and sprawl out outside of their kennel. This also allows them space to observe their humans.
Transitioning your bunny to its new home
One thing to remember, Is like any animal, rabbits do take some time to warm up to their new home. We average it to be around 3-4weeks for them to claim their territory and get used to their new surroundings. Around this time you will see their personalities really blossom.
If given too much space too quickly, rabbits will "mark their territories" with their poos. You want to slowly give them more and more space to gain a good Free Roam area for them.