iPhone 15 Plus is the cheapest 6.8 inch iPhone.
The USB port has support for PD ( power delivery) for up to 4.5 W, to charge accesories, or if you pair 2 phones capable of PD (iPhone 15 or Android) the phone with less battery will charge slowly from the one that has more battery, or it the other phone doesn t support PD the iPhone will work as a power brick.