Yes, you can use an old USB-A charger with your iPhone 14 Pro or even iPhone 14 Pro Max. That said, all the iPhone 14 models come with a USB-C to Lightning cable in the box. This cable won’t work with an old charger, so you’ll have to buy a new charger. Also, the USB-A charger won’t power up your iPhone at more than 18W. If you are moving from an iPhone 13 or already have a fast USB-C charger then it should work fine with the iPhone 14 series.