The battery in a 2017 Buick Enclave is located behind the front passenger seat. To access the battery, you’ll need to pull up the floor mat, pop off the plastic covering, and then open the panel on the floor. Inside, you’ll find the car battery.
If you’re looking for the battery because you need a jump-start, then don’t bother excavating the battery—you can just use the jump peg attached to the fuse box—which is under the hood.