Control nearby Apple devices with Apple Watch? You can, with a function present in the accessibility settings, aimed at people with motor disabilities.
However, the setting opens up to various other uses. For example you can use nearby iPhone or Apple Watch for pause or resume playing a movie.
What needs to be ensured is that the iPhone or Apple Watch it is controlling, and the device being controlled use the same Apple ID. Furthermore, you must also make sure that WiFi and Bluetooth are active on both devices.
At this point, on the iPhone just open the Settings app and then tap on Accessibility. Here you will find the option “Check for Nearby Devices”: the devices should appear in the list. Once connected, you can access the panel with all the settings and controls.
Attention: Apple specifies that it is not possible to control the iPhone with the iPad or the Mac with the iPhone and Apple Watch.
According to the latest rumors, watchOS 10 will allow you to pair Apple Watch with multiple devices and not just an iPhone.