iPhone 15 USB-C port can output significantly more power to accessories than Lightning
iPhone 15 and iPhone 15 Pro will charge at 27 watts over the USB-C port. That means you can charge your phone from 0 to 100% in under two hours with a USB-C cable and . However, that is unchanged from the iPhone 14 series which could charge at the same speed over Lightning.
What is different though with USB-C is that the iPhone can now output significantly more power to accessories. Via Macotakara, iPhone 15 will be able to output up to 4.5 watts to accessories via USB-C.