There was a video by PolyMatter recently on the economics of why Apple cannot yet move the bulk of iPhone manufacturing away from China (available on Nebula and on YouTube). This is perhaps the singular quote which helps answer your question, around the 02:35 mark:

Any country can assemble the iPhone. But Apple doesn’t need to make an iPhone, it needs to make 590 every minute, it needs 35,000 per hour, 849,000 per day, 5.9 million per week. That’s the challenge facing Apple.

The sheer scale of Apple’s manufacturing – setting aside Samsung’s also humongous scale – means that there might not be a supplier for that quantity of large image sensor or new-tech batteries. Now, Apple could drive that sort of market, and they probably are working on it. But as the video explains, Apple’s style is more about finding an edge which they can exclusively hone, up to and including the outright buying out of the supplier. This keeps them ahead of the competition, at least for long enough until it doesn’t matter anymore.

In some ways, this might sound like Apple has a touch of Not Invented Here Syndrome, but realistically, consumers expect that Apple is going to do something so outlandish and non-standard that to simply be jumping onto a bandwagon of “already researched” technology would be considered a failure. They are, after all, a market leader, irrespective of what one might think about the product itself.

Historical example of heavy R&D paying dividends until it stopped being relevant: Sony’s Trinitron CRT patent expired just around the time that LCDs started showing up in the consumer space. Any competitor could finally start producing CRT TVs with the same qualities as a Sony Trinitron TV, but why would they? The world had moved on, and so had Sony.

In brief, Apple probably can’t deliver an iPhone with massive image sensors right now. But that certainly doesn’t mean they wouldn’t have their camera team looking into it and working with partners to scale up the manufacturing, such as by increasing yield or being very clever, probably both. Ever since that one time an iPhone prototype was found in a Bay Area bar, their opsec for new prototypes has been top notch. So we’ll only know when we know.