If you’re using a 3D Touch-capable iPhone, with iOS 10 you can now choose from three different intensity levels for the LED flashlight by using a 3D Touch gesture on the Control Center button.
To do this, swipe from the bottom of the screen to bring up Control Center, and use a 3D Touch press on the flashlight button and you’ll get a menu with options for Bright, Medium, or Low light. You can access this menu to change the setting regardless of whether the flashlight is already on or not, and your iPhone will remember the last setting you used when you next toggle the flashlight on again.
