Do this for me: hold your phone 9-12 inches from your face and stare at it. Then alternate closing your left and right eyes. See the screen jump left and right? That jump is the amount an image can appear to leave the screen. The photograph is showing you the image of the phone the left eye sees and the image of the fish the right eye sees. The image itself is a fake of course, but it’s likely somewhat close to what it would be like to view the actual 3D display.
Do this for me: hold your phone 9-12 inches from your face and stare at it. Then alternate closing your left and right eyes. See the screen jump left and right? That jump is the amount an image can appear to leave the screen. The photograph is showing you the image of the phone the left eye sees and the image of the fish the right eye sees. The image itself is a fake of course, but it’s likely somewhat close to what it would be like to view the actual 3D display.