Lower the landscape, keep the climate
The guiding principle for an elderly bearded dragon's vivarium is that his needs have not shrunk — only his climbing has. He still requires the same basking heat and the same UVB exposure as a young dragon, so the answer is never to remove the basking spot; it is to bring it within reach. Swap a tall basking stack for a low, wide platform he can walk onto up a gentle slope, and position the UVB tube so its effective distance reaches him at that lower height — UVB weakens with distance, so lowering the dragon without adjusting the lamp quietly under-doses him. Check the basking temperature at the new surface, not where the old one was, because the whole point of the change is the spot he actually uses now.
Ramps and grip instead of climbs and leaps
Young dragons scramble up branches and leap down without consequence; elderly ones fall, land badly, and can injure limbs or spine. Take out tall, narrow climbing branches and anything he could topple from, and replace the vertical interest with horizontal: wide ramps of cork bark or textured wood at shallow angles, low hides he can walk into rather than climb onto, and flat basking stones with a surface his claws can bite into. Test every surface with his body in mind — if a ramp is smooth enough that his claws skate on it, roughen it or choose another material. A dragon who feels secure underfoot moves around his enclosure; one who keeps slipping retreats to a corner and stops exercising altogether.
Flooring an old body can walk on
Substrate choice matters more with age. Very loose, deep substrate that a young dragon digs through happily can exhaust stiff legs and make every crossing of the enclosure a wade. A firmer surface — well-packed suitable substrate, or textured tile or liner in the areas he walks most — gives him purchase without removing a dig area entirely; many keepers keep one corner of diggable substrate so the behaviour survives without taxing every journey. Keep the floor clear of small obstacles he would have to climb over between the key places in his day, and watch for worn claws or sore-looking feet, which are often the first sign the flooring is working against him.
Food, water, and rest within a short walk
Arrange the three stations of his day — basking platform, food and water, and his preferred hide — in a compact triangle he can cover in a few unhurried steps. An elderly dragon who must cross the whole vivarium and climb to eat will quietly eat less, and one who cannot face the journey to bask will sit cold in his hide and digest poorly. Put his salad dish on the floor at his level rather than on a ledge, set the water dish where he passes it, and make sure the hide he sleeps in is one he can enter at ground level with room to turn around. Then watch him use the layout for a few days: the places he struggles, hesitates, or avoids are your instructions for the next adjustment.
Keeping the Adapted Layout in Place
An adapted vivarium only works if everyone in the household treats it as the setup — a well-meaning family member who puts the tall branch back, moves the food dish up, or returns him to the top of a basking stack after handling undoes the point of it. Share his profile with the family members you choose through KinsLe's Family Sharing, so a relative who feeds or handles him has access to that profile rather than a secondhand account of this elderly dragon. Revisit the layout every few months: ageing is a moving target, and the vivarium that suits him this season will likely need its ramps shallowed and its journeys shortened again before long. With KinsLe Family Sharing, the relatives you pick can open his profile themselves — his, and no other dragon's — whenever they come to feed or handle him.