Yes — with one preparation rule
Sweet potato is a genuinely useful food for a bearded dragon, as long as it reaches the bowl cooked. Raw sweet potato is dense, starchy and stubborn stuff for a reptile's gut, the kind of thing that can pass through half-digested. Cooked plain until it is soft all the way through, it becomes an easy, well-accepted rotation food that most dragons tackle happily, and its color alone draws interest from dragons that pick half-heartedly at plain greens.
What sweet potato actually brings to the bowl
The headline nutrient is beta-carotene, the plant pigment behind the orange flesh, which the dragon's body converts toward vitamin A as needed. Arriving in that plant form matters: the dragon takes up what it requires rather than being flooded in one sitting. Sweet potato also brings fibre and useful energy. What it does not bring is much calcium, and it is filling in the way starchy foods are — a dragon that loads up on sweet potato cubes has less room, and less appetite, for the leafy greens carrying the calcium load. That is the honest trade: a nutritious extra, never the foundation.
Cook it plain, cut it small
Bake or steam a sweet potato with nothing added — no oil, no butter, no seasoning, nothing sweetened — and let it cool completely before it goes anywhere near the enclosure. Peel away the skin, then cut the soft flesh into small cubes your dragon can take in one bite, or mash a spoonful loosely through the day's salad so it coats the leaves. If you mash rather than cube, mash it coarse — the dragon should still be picking up distinct pieces, not lapping at a purée it can smear around the bowl. Offer a few cubes scattered over a normal bowl of staple greens rather than a dish of sweet potato alone. A cooked batch keeps in the fridge for several days of easy portions, but once a serving has sat in the warm enclosure, leftovers come out the same day; cooked vegetables sour fast under heat lamps. A light dusting of calcium powder over the salad on sweet potato days is a sensible pairing, since the cubes themselves contribute almost none.
Where it fits in the week
A few small servings a month suits most adult dragons — think of sweet potato the way you would butternut squash or pumpkin, its close cousins in the rotation: dense orange vegetables that add variety and beta-carotene between the green staples. Offer it in the earlier part of the day, while the dragon is warm from basking and digesting at full tilt, rather than as a last-minute extra it has to process as the enclosure cools. Young dragons still building their growth on insects need only a taste now and then. Read the results in the bowl and the droppings: if your dragon starts leaving the greens and hunting the orange cubes, or the stool loosens on sweet potato days, the portion is too big or arriving too often, and the fix is simply to shrink it and space it out.
Noting sweet potato's slot in the rotation through KinsLe's Care Teams — cooked, cubed and occasional — means the dragon gets its orange variety on schedule instead of whenever someone happens to find a spare one in the kitchen.