It is considering a triple-lens camera design for its most expensive new smartphone, while the cheaper model could benefit from a rear dual-lens camera system.
The news, first reported in the Wall Street Journal, comes as sales of the iPhone in China continue to suffer. Apple chief executive Tim Cook confirmed in a letter to shareholders last week that the company was cutting its quarterly revenue target after a major sales dip in the country.
On Chinese online retailer Suning, owned by Alibaba, the iPhone XR was available at a discount of up to 20 per cent to add an incentive to would-be buyers.
Apple only released its new iPhone XR in October, and discounts are unusual on its latest iPhones.
Last week, Apple confirmed it expected sales over the Christmas quarter to be down to US$84 billion ($122.9b), down from its earlier estimates of between US$89b and US$93b. It is only the second time Apple had revised its earnings since 2002.