Apple’s MagSafe Duo Charger is a compact, square-shaped charger for the iPhone (or other Qi-certified devices) and the Apple Watch. According to Apple: “The MagSafe Duo Charger conveniently charges your compatible iPhone, Apple Watch, Wireless Charging Case for AirPods, and other Qi-certified devices. Just place your devices on the charger and a steady, efficient charge begins on contact. The charger folds together neatly so you can easily take it with you wherever you go.”
The charger ships with the MagSafe Duo Charger and a 1 m USB-C to Lightning Cable, but no charging brick. Therefore, the MagSafe Duo Charger does not charge out of the box without pairing it with an existing plug.
An Apple Support article specifies that “Your MagSafe Duo Charger is designed to work with all iPhone 12 and iPhone 13 models, all Apple Watch models, Apple MagSafe accessories, and Qi-certified devices and accessories.” The article goes on to state that you should “Use the included USB-C to Lightning cable to plug in your MagSafe Duo Charger to a recommended 20 watt (W) or greater Apple USB-C power adapter,” but the “Apple 29W USB-C Power Adapter isn’t compatible with the MagSafe Duo Charger.”
The Apple Watch charging side “…can charge your Apple Watch in a flat position with its band open, or on its side, by lifting the inductive charging connector. When docked on its side, your Apple Watch automatically goes into nightstand mode, so you can also use it as your alarm clock.”
Source: Apple, Apple Support