Are there any descendants of King Louis XVI?

No, since the Merovingian dynasty ended in 751. This was followed up by the Carolingian dynasty, which ended in 1122 amd this was followed up by the Valois dynasty and this ended in 1482. Eventually this was followed up by Bourbon dynasty and this was the dynasty that King Louis XVI belonged to. He reigned from 1774 until 1792 and this was the last monarchical dynasty of France.