As of writing, most of the major carriers are offering free iPhones with unlimited data plans if you're willing to trade-in your current device.
For example, both AT&T and Verizon are currently offering up to $1,000 off a shiny new iPhone 14 Pro right now, which is more than enough to cover the entire cost of the device. For those not looking to trade, Verizon also offers the iPhone 14 Plus for free with an unlimited data plan - an awesome deal that's not tied to the usual trade-in either.