How do I show a horizontal line while using the camera on my iPhone?
How a horizontal line can be shown while using the Camera - for helping taking accurate Fotos?
[Re-Titled by Moderator]
iPhone 15 Pro Max, iOS 17
Question marked as
You can enable a grid in the Settings > Camera, and there is also a Settings > Camera > Level to show an additional horizontal line. This line will be broken, if the camera is tilted.
Use iPhone camera tools to set up your shot – Apple Support (UK)
Use a grid and level to straighten your shot
To display a grid or level on the camera screen that can help you straighten and compose your shot, go to Settings 
> Camera, then turn on Grid and Level.
After you take a photo, you can use the editing tools in the Photos app to further align shots and adjust horizontal and vertical perspective. See Straighten and adjust perspective.