There have been some rumors suggesting that the next generation of iPhones would, like the iPad Pro 2018, switch to USB-C for their singular data/charging/audio connection. However, the latest leak on the subject contradicts them again, claiming that Apple will stick with its proprietary Lightning connectors for the upcoming flagships.
https://www.notebookcheck.net/2019-iPhones-will-stick-with-Lightning-port-new-leak.396521.0.html