On the iPhone: Settings > General > About. The model is under “Model Name”.
On the iPad: Settings > General > About. The model is under “Model Name”.
Turn the Mac over: the model number is printed on the bottom, and on an iMac, under the stand. It is an A followed by four digits, for example A2681. Type it in “Search model” or find it in the list. If the Mac turns on, you can also open the Apple menu (the apple, top left) and choose “About This Mac”.
On the paired iPhone: Watch app > General > About. It also appears on the watch, in Settings > General > About.
The name is usually on the device, its box or the receipt.