When it comes to using your iPhone at night, you have a few options. You can enable Night shift to keep it simple. Colorect, Color Tint, allows you to turn your entire display red, which is surprisingly effective for late-night browsing.
Color Tint is quite different from the Night Shift mode you get to sleep easier by canceling out blue light frequencies, resulting in an orange hue.
Red light is harder to see than other light frequencies so it tricks our eyes into thinking it's less bright than it really is. This means you can look at a red screen in a dark room. Additionally, in the end, the iPhone's hidden Color Tint feature might be awesome for using for some amateur astronomy, sneaking a quick peek at your iPhone in a movie theater, or just checking your device when you wake up in the middle of the night.
HQRP High Power Tactical 3W Red LED Flashlight with Adjustable Focus.
HQRP High Power Tactical 3W Red Flashlight with Adjustable Focus
: Enable Red Tint
To try out the hidden feature, simply go to Settings -> General -> Accessibility -> Display Accommodations. Here, you will find the new location of the "Auto-Brightness" toggle as of iOS 11 and higher, but for the red tint, you'll want to select the "Color Filters" option.
Next, enable "Color Filters" with the switch at the top of the screen, then select "Color Tint" as your filter. Intensity and Hue sliders to make the red effect more prominently.
The effect can not be captured in screenshots, but it's certainly dramatic. And because your iPhone is just red light, it wants to be much easier to use in dark environments.
Step 2: Add a Shortcut for Your Red Tint (Optional)
If you find yourself wanting to go back and forth between your new tint and regular non-tinted screen, it's pretty much inconvenient to keep going into the "Color Filters" menu in Settings to Toggle the red filter on and
To speed up this unnecessarily long process, you can enable Accessibility Shortcut and just triple-click the Home button (or Side button if it's an iPhone X, X S  X S Max, or X R ) to toggle the red screen on and off instead.
To set it up, go to Settings – > General -> Accessibility, then scroll all the way to the bottom and select "Accessibility Shortcut." Choose the "Color Filters" option from the list and you're done. Now every time you triple-click the Home button, it'll switch between normal screen and red-tint.
If you're using one of iOS's other secret features or another Accessibility Shortcut like Smart Invert Colors, then when you triple-click the Home button ), a menu will pop up asking you which to choose instead.