Apple Watch's Cinema mode stops the screen from illuminating every time you move your hand. See how you can set an automatic process that will stop the lighting.

If you do not want the Apple Watch to turn on when you are at work or relaxing in bed before going to bed, you can turn on Theater mode automatically.
Theater mode can be activated manually from control Center on the Apple Watch. Dragging up from the home screen of your watch to reveal the Control Center.

Then tap the "Theater" icon to activate the feature.

Using the Shortcuts app, you can save a few taps each day. Create an automation that automatically turns Theater Theater on or off at a given time. This feature is available for the current Apple Watch Watch 7 or newer versions. On the iPhone side, you should be using at least iOS 14 or later.
Open the "Shortcuts" application on your iPhone and go to the "Automation" tab.

Here, press the "+" button in the upper right corner.

Select "Create Personal Automation".

Select the "Time of Day" option.

Set the time you want to activate Theater mode. If you want the automation to work on a daily basis, select the "Daily" option Then, click the "Next" button in the upper right corner of the screen.

It's time to dump her and move on. Click the "Add Action" button.

Search for and add “Set Theater Mode” or “Set Cinema Mode”. The feature has a different name per region.

By default, the "On" option is selected.

If you are creating the automation to turn off Theater mode, press the "On" button and select "Off" from the pop-up message.

Now, click the "Next" button.

To make this automation truly automatic, press it switch next to “Ask Before Running” to turn off the requirement.

Select the "Don't Ask" button from the pop-up message.

Now, click the "Done" button in the upper right corner to save the automation.

You can repeat this procedure to create another automation to turn off Theater mode. Make sure you select "Off" from "Set Theater Mode".
When the shortcut is activated, you will receive a notification about it.

You can enable shortcuts depending on your location, battery level and more.
Source of information: howtogeek.com