I'm reading a novel on a website that offers 2 chapters at a time. I use the Safari browser on my iPad.
If I happen to wake late night/early morning and want to read, the Safari app is way too bright. Other apps' brightness can be turned down with the timed night shift found at Display and Brightness under settings. For some reason, Safari is still too bright for my night eyes.
I found a fix:
Settings
Go to Accessibility
Go to Display and Text Size UNDER ACCESSIBILITY
Scroll down to Reduce White Point
Turn it on and set the slider to a % reduction in intensity
See screenshot where I have mine turned down to 84%
Note: This affects colors so when working with an App where color is important like Procreate, turn this off.
Note2: There is also a setting to Differentiate Without Color for color blind assistance.
Although the settings menu arrangements change slightly with Apple updates, the following 2019 article was helpful in figuring this out:
https://www.businessinsider.com/how-to-lower-brightness-on-ipad-even-more