That means users have no dedicated key for adjusting some system settings, including keyboard backlight brightness. Fortunately, Apple has included a setting in iPadOS that lets you do this manually.

Press the F5, F9, or F11 key to turn your HP laptop keyboard light on or off. Some HP laptops need the Fn key pressed with ...

If you cannot turn on the Backlit keyboard or the keyboard backlight is not working in Windows 11/10 desktop or laptop, see this post.

If your model has a Touch Bar on the keyboard, expand the Control Strip, then tap the increase brightness button or the decrease brightness button. To turn to backlight off, touch and hold.