OLED cannot sustain peak brightness compared to LCD.
Apple limits the brightness when you use the brightness slider. Max brightness on iPhone 11 Pro can only be achieved if you shine a bright light into the ambient light sensor.
If I disable Auto Brightness, my display is a lot more vibrant and brighter at the same brightness level. Easier to notice against a white background like Google.com. It’s a big difference.
With auto brightness on, the screen is a lot duller and dimmer than my iPhone X or iPad Pro. With it off, it is a lot brighter. Turning auto brightness on/off makes zero difference in brightness to my iPhone X/7/SE/8 or any of my iPads (or Pros).
Can you please check if your iPhone 11 Pro (or Max) behaves the same way?
Thanks so much. God Bless!
Aakshey
Can you try this?
You will need to wait for 30 seconds after turning it off for the effect to be visible.
Your brightness level should be less than 100% and more than 0% for this test.