I think so. I use a baby pool for my sulcata, who is 10 inches long. It's the large hard plastic kind. I put it on uneven ground and put enough water in to form a puddle on one end. I also add shade (a portable patio umbrella). That's for unsupervised outdoor time. If I can be outside, too, I put a helium balloon on him (tie it around, tape into place at the plastron) and let him wander around the yard.
Yea it's the hard plastic kind. Omg I bet that is so cute to see you tort with a balloon!
"what are the dimensions of the baby pool? and how big is the tortoise?"
I don't know right now how big the pool is, my tort is about 4.5 inches.
Just be sure if you use the wading pool to put some drainage holes in the bottom. If an unexpected heavy rain shower comes along, it does not take long for them to fill with water deep enough to drown a tortoise. Also keep in mind when choosing a location for it, they do seem to get warm quickly, so heat may be an issue.