"Có nhiều cát ở đâu" có dung không
Yes but it sounds awkward. You could also ask:
"Nơi nào có nhiều cát?" Nơi = place, location.
"Chỗ nào có nhiều cát?" Chỗ = place, location
The English sentence "Where has a lot of sand" is also awkward. It should be similar to your Vietnamese sentences that you presented: "What place/location has a lot of sand?".
Yep or simply "Where is there a lot of sand?"
where has much sand