The rumoured foldable iPhone was speculated back in March 2018. When Bank of America Merill Lynch told CNBC that Apple was working on a foldable iPhone with its Asian partners. The patent itself shows a display with hinges located in the middle. Indicating the folding point of the display. The illustration suggests that the display can be widely used. In devices including phones, tablets, laptops, wearables, and even mobile accessories. Apple wrote about the possibility of using flexible display technology to improve electronic devices. This may be hinting at future devices with such technology.
As these things usually go, the patent is merely a concept, with no indication as to when or if Apple will even implement the design in future devices. Further, and at the time of writing, Apple has not responded nor released any announcement about the subject. (Source: The Verge, CNBC)