I recently reviewed the SANDMARC wide angle lens kits that gives iPhone 7 Plus or 8 Plus users the ability to take advantage of a wide angle focal length. 16mm equivalent to be exact:
If you're interested in checking it out for yourself, hit the link below.
Check out these samples. All photos take with the iPhone 7 Plus on the 12MP wide-angle ƒ/1.8 aperture lens and using the SANDMARC wide angle lens.