Apple introduces new features in the support page, explaining the capabilities of the iPhone 15 that result from the switch to USB-C port. While other smartphones with USB-C may have been able to do this for a while, the iPhone 15 offers the ability to charge other devices. The condition is that the device must be small and use a maximum of 4.5 watts of power, such as AirPods or Apple Watch.
Additionally, the iPhone can now be connected to an external display, supporting up to a 4K 60Hz screen when using USB-C and DisplayPort or USB-C Thunderbolt 4 cable with the iPhone 15 Pro, which also supports USB 3.1. Furthermore, the display settings can be adjusted between SDR and HDR.
TLDR: Apple introduces new capabilities for the iPhone 15, including the ability to charge small devices and connect to an external display with up to 4K resolution and adjustable display settings.