Of course, Apple has not announced anything yet.
The rumor mill is that Apple is adding one additional camera to the two they already have. The current cameras have approximately 26-28mm (wide) and 52mm (normal/portrait) equivalent lenses. One rumor suggests that the new camera will use a wide angle lens, as LG has been shipping for years, and pretty much every 3-camera phone does. So this seems to just be keeping up with the Jonses.
The one interesting thing about the rumor is that it’s suggested the wide angle camera will be higher resolution. This makes sense.
Pretty much every “portrait” camera is a smaller, lower quality camera versus the main camera. Including Apple’s. Why? The typical standard phone camera has a 4.0-5.0mm lens. In order to deliver a 2x portrait lens on the same sensor, they would need to double that to 8.0-10.0mm, a neat trick to fit in a 7-9mm thick phone. So they shrink the sensor and probably use about a 6mm lens.

Going the other way, LG’s wide angle lenses have been around 2mm… and they use a normal sensor. But they could use a larger sensor with more resolution and still easily fit within the confines of the phone. So this might be a little bit interesting.
The other rumor is that the new iPhone’s third camera will be a “3D” time-of-flight depth sensing camera instead. Sony has developed these, and most premium phones use Sony cameras, so it stands to reason any company making premium phones would know about this option. A few of the newer Android phones have ToF cameras. Better 3D models are important for augmented reality applications.
The rumors also suggest a prominent camera hump, which is very contrary to Apple’s entire design language history. So take that with a shaker of salt.
But these are just rumors right now. If Apple’s releasing new iPhones in September as usual, it’s way too early in March for Apple’s typical strategic leaks. So either this is a fantasy or it originated with people outside of Apple.