The technology giant is thought to have an iPhone X Plus in the pipeline, and also plans for a iPhone SE update, both of which are expected to be bigger than their predecessors, with the latter set to target the mid-range segment.
A new report by technology analyst TrendForce, obtained by 9to5Mac, states: "New iPhones in 2018 will continue to improve Face ID technology, screen to body ratio, etc.
"Moreover, the company plans to increase the memory content and embed AMOLED display in two of its models.
"In order to meet the demand in different ranges of market, Apple will launch the second generation of iPhone SE which targets at the mid-range segment."
TrendForce has also estimated iPhone production will increase by 7.5 per cent in 2018 after 2017 iPhone production went up by three per cent over 2016.
And while Samsung smartphone production was also up by three per cent in 2017, the tech analyst expects sales to drop by the same amount this year.
TrendForce added: "As the industry leader, Samsung will remain the top for smartphone production in 2018, but will witness a three per cent drop in production volume because of great challenges and fierce competition brought by its rivals, including Apple in high-end market and a number of Chinese brands with Android OS."
This comes after Apple confirmed all batteries for iPhone 6 models or later can now be swapped for $29, regardless of the results of a diagnostic test.