You do not need to unlock an Android phone to turn on its flashlight. Samsung Galaxy and Google Pixel devices offer several shortcuts that provide quick access from the lock screen or notification controls.
On both types of phone, you can also use Google Assistant hands-free. Say “Hey, Google” and then ask it to turn on the flashlight.
Google Pixel phones include the flashlight in the Quick Settings menu. Swipe down from the top of the screen and tap the flashlight icon to activate it; tap the icon again to switch it off. If the control is not visible among the first options, tap the pencil icon at the bottom of Quick Settings, then add the flashlight control or move it higher in the menu.
Pixel users can also assign the flashlight to the Quick Tap gesture. Open Settings > System > Gestures > Quick Tap to start actions, enable the flashlight option and then double-tap the back of the phone to toggle it.
Another option is to add the flashlight to the lock-screen shortcuts. Press and hold the lock screen, tap Customize, scroll to Shortcuts and select the flashlight icon.
On Samsung Galaxy phones, swipe down from either top corner to open the Quick Panel and tap the flashlight control. If it is missing or you want to change its position, open the panel and tap the three-dot menu or pencil icon to edit and rearrange the controls.
Samsung also lets users replace one of the two lock-screen corner shortcuts, which are typically assigned to the Phone and Camera apps. Press and hold the lock screen, select one of the shortcuts and choose the flashlight. If lock-screen editing is unavailable, go to Settings > Lock Screen & AOD and enable Touch and Hold to Edit.
Sources: Engadget.