If you control your ambient lighting or use automatic adjustment, you don’t have to.

I can count on one hand the number of monitors I've seen with auto brightness. The number of monitors with acceptable and non distracting auto brightness is zero.

I mean, if you have a modern digital display you might be able to change the brightness through the DDC/CI protocol and a simple app or extension, available in every much every OS. With a keyboard shortcut or two clicks you change it. Fiddle with monitor settings is painful, but that protocol is a godsend. Even one of my cheapest 13 years old monitor supports it.