You may have noticed the default lowest brightness setting on iPhone is still quite bright, especially at night. Luckily there’s a slightly hidden setting that can reduce that further, and with the power of Shortcuts makes quite a nifty low light ‘extra dim’ switch.
Reduce White Point is the setting, and can be found under Settings → Accessibility → Display & Text Size. Using Shortcuts you can then make a quick and easy toggle, and activate in your favoured way – whether through your Action button, a Siri command, or home screen widget.
For an even more robust night time automation, consider combining with turning on Dark Mode and changing Brightness to 0%.