There is a setting, so I can tap three times with three fingers each time top open a menu and set a filter, and I choose low light mode

It's not the easiest mode to find, but works.

You can configure iOS Home button triple-click to invert the screen, so it's white text on a black background. There is a "Smart Invert" option so that photos are not affected.

You can also apply an accessibility filter to increase the darkness in iOS. I have this mapped to a triple home-button click and use it all the time (after reading to kids etc)

https://www.techrepublic.com/article/pro-tip-dim-your-ios-sc...

I'm on X so no more Home button, but good suggestion. For last 9 months I had my phone on grayscale, which was nice, but still a bit high for my taste.

You can go further by reducing white point in accessibility settings. The colour filters there also go beyond night shift.

Interesting. I was on grayscale for last couple of months, but didn't know I can reduce the white point also. Will try.