Have fun with your pool!
It is possible that chickens may investigate the pool sides, and if there are any specks or bugs on the sides, they may peck/eat them. They also may hang out by the pool due to the shade on whatever side and coolness offered by the large mass of water. They like to dig their dusting holes and mine often do this in the shade.
Since you’ve likely prepared the ground to be level, you would want the chickens to stay away from the dirt foundation and not dig next to the pool. Surrounding it with a short fence or just laying pavers around will keep them from digging too close to the pool. The short fence would keep them away from the sides.
If you only do one thing, I would lay pavers or something around the perimeter to keep them from digging dust holes next to the pool base.. They really enjoy their dust baths!!