What is the mm on the iPhone 6 Plus front and back camera?

So when I take a pic arms length everything seems distorted so I'm guessing it's not how you really look like in real life?

It's around 4 or 5mm which converts to about 28mm in 35mm format. Yes, this is very wide and will produce a great amount of wide-angle distortion.

Yes, the wide angle lens will distort anything that is relatively close to the lens, like arm's length. The more you back away from the lens, the less noticeable the distortion.

A phone camera is really good for fender benders. If you want an honest result of a human being you want a camera with at least a 18-70mm lens. The 70mm end will give you the proper persective to render a human "normal" looking.

Wide angle at arm's length is severely distorted. Let someone else take your picture using a real camera.