Have you seen the documentation page for it here?
This is something that is on by default. If you want to control it by using the settings you’ll need to add a post process to your scene that covers any areas you want to be affected by it. You’ll then check the boxes with the ones that you want to override the default values with. In this case you’ll locate Auto-Exposure and enable it along with any of the other choices there and change the settings to fit the look you want.