Just as you can on your Apple Watch.
Go to Accessibility > Control Nearby Devices.
Your iPhone or iPad must be signed in to iCloud with the same Apple Account and be on the same network.
Choose a device if more than one is nearby, then tap a button.
Buttons replicate the controls on your device and include the following:
Home button
App Switcher
Notifications Center
Control Center
Siri
Options (includes media play controls and customizable hand gestures)
When VoiceOver is enabled on your Apple Watch and you control a nearby device, VoiceOver will also be enabled on that device, and the VoiceOver gestures that you use on your Apple Watch are performed on the device.
Similarly, when Switch Control is enabled on your nearby device, Switch Control buttons appear on your watch (Move, Next, and Select buttons, for example).