The Wall Street Journal reports the tech giants are working on a successor to the XR model, featuring an LCD (Liquid Crystal Display), and two other models with the aim to provide better cameras on the devices.
The higher priced version of the XR will reportedly feature a triple rear camera and the two lower priced models, a double rear camera function.
There is also talk of them using OLED (Organic Light-Emitting Diode) screens in the place of LCD in the future.
Apple has refused to comment on the news.
Tim Cook's firm sold less iPhones than expected in 2018.
Apple also confirmed it will no longer give details of unit sales for its major devices - including iPhones, iPads and Macs.
Although iPhone revenue had soared, it appeared the sales figures had fallen short of what was predicted.
The initial results saw Apple shares drop around four per cent, and then there was a further decline - more than seven per cent - after the earnings call revealing the new reporting structure.
Apple revealed it had sold 46.9 million over the quarter ending September 29, which was similar to last year's 46.7 million.
However, the price boost appeared to help the company as iPhone revenue rose 29 per cent to $37.2 billion.