Hi
Turning Silent Mode on or off cannot be mirrored across your Apple Watch and iPhone.
Silent Mode can instead be enabled via Control Centre on your Apple Watch either directly or when turning on Theatre Mode. Control Centre is accessed by swiping up on the screen when viewing the time on your watch:
- Use the Control Center on your Apple Watch - Apple Support
- Change the audio and notification settings on your Apple Watch - Apple Support
- Adjust brightness, text size, sounds, and haptics
- Be a considerate moviegoer with Theater Mode
You may otherwise be referring to Do Not Disturb Mode.
In addition to being able to turn Do Not Disturb mode on and off via a button within Control Centre, your Apple Watch and iPhone can also be configured such that enabling the mode on one device also enables it on the other.
This mirroring setting also applies to scheduled operation of Do Not Disturb mode on your iPhone, which you may have enabled (such as to cover the hours when you are usually sleeping):
- On your iPhone, in the Watch app, go to: My Watch (tab) > General > Do Not Disturb - turn on / off Mirror iPhone.
- On your iPhone, go to: Settings > Do Not Disturb - turn on Scheduled to set your preferred times.