Charge an iPhone (with Lightning port) from an iPad (with Lightning port)

Suppose you have: 1. An iPad (7th Generation) with a Lightning charge/sync port, and 2. An iPhone 7, also with a Lightning charge/sync port. The iPad battery is fully charged; the iPhone battery is empty (or close to it). Is there anyway to charge the iPhone from the iPad? I know that if you are using an iPad with a USB-C port, you can use a USB-C to Lightning cable to charge the iPhone . But what if you have an older iPad model without a USB-C port? An older iPad can definitely charge a 1st-generation Apple Pencil through its Lightning port, so there must be some kind of reverse-charging capability there. Is it possible to charge an iPhone (or, I suppose, any other iOS device with a Lightning port) from an iPad with a Lightning port?