how do i stop unwanted messages from texts during the night?

Just open Control Center on your iPhone, or on your iPad, touch and hold Focus, then select the Focus you want to turn on.

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Turn on Focus

1. Go to Settings > Focus.
2. Tap a provided Focus option—like Do Not Disturb, Personal, Sleep, or Work—then tap Customize Focus.
3. Set up your Focus.

Use Focus on your iPhone or iPad - Apple Support (IN)