You can adjust brightness by swiping from the right edge to bring out the notification bar (called action center) and then tap the brightness tile to switch thr

You can adjust brightness by swiping from the right edge to bring out the notification bar (called action center) and then tap the brightness tile to switch through five modes of brightness. It's not a slider but it does the job well. That said overall the tablet experience on Windows 10 is not ready for prime time. I get weirdness with the on-screen keyboard as well as quirks with Explorer and so on.