Illustrations from Apple’s patent application for an iPhone Flip hinge. Image credit-USPTO
The illustrations show a non-descript clamshell phone that folds around a vertical axis similar to the Galaxy Z Flip phones, the Motorola Razr models, and other phones that fold in this manner. The hinge moves both inwards and outwards although the former is the movement most associated with clamshell foldables. Some outward folding devices, like the Honor V Purse, do exist.
The patent application mentions parts such as friction clips and synchronization gear plates. The patent submission doesn’t mean that Apple is definitely working on an iPhone Flip. After all, it submits many patent applications a year and only a small percentage of them ever become products or parts of a product.
Apple might consider creating a clamshell foldable iPhone before a book-style foldable. That might be due to the sales data which shows that the clamshell Galaxy Z Flip has been the best selling foldable over the last three years beating out the Galaxy Z Fold models.