You might be confounding a RAW photo file and the way it is displayed. A RAW file isn’t even actually an image file, it’s a container containing the sensor pixel information, metadata, and a pre-generated JPG thumbnail. To actually display an image, the viewer application either has to interpret the sensor data into an image (possible with changes according to its liking) or just display the contained JPG. On mobile phones I think it’s most likely that the JPG is generated with pre-applied post-processing and displayed that way. That doesn’t mean the RAW file has any post-processing applied to it though.