How to adjust Android Pie’s adaptive brightness feature

Sometimes new features that come with updated operating systems turn out to be more trouble than they’re worth. Take Android Pie’s adaptive brightness mode, which is meant to intelligently adapt your phone’s display to your lighting preferences. For some people, it works. But if you’re not one of those people, you can just turn it off.
I recently bought a Pixel XL phone — yes, I know: it’s way out of date, but it was really cheap — that runs Android 9 P