Most mobile devices running Android Lollipop (5.1.1) have the ability to shoot photos in the RAW format.
A RAW file is an uncompressed/unprocessed photo, which includes all the image data captured by the camera of your device. While RAW files are heavier in size, they can be edited (white balance, sharpen, colors...) without major lost in terms of image quality (requires a specialized image editing software).
Here's how to enable RAW support for the Camera app of your Android smartphone (tested on the LG G4):
Open the Camera app. Tap on the Ellipsis button and then select the Manual mode. Tap once on the JPG button (default format) to switch to RAW JPG.
That's it; RAW support is enabled, simply adjust your settings (ISO, Shutter speed...) and shoot your photos.