For example, like warmer night colour opening at sunset, why not opening keyboard backlight at sunset?
Can you rephrase? Do you mean having the keyboard backlight turn on automatically?
Yes, sorry…English is not my mother tongue
Or turning on backlight if its evening and I click on keyboard.
Does your device support anything like this? But I don’t have any peripherals with lights, so I might not be able to help you.
I can manually open/close it by
Fn+Space but I want to know if there is some automatic way.
This sounds like you want Redshift from community repository
@nikgnomic Redshift is used to control the screen colour, not keyboard backlight.
The best place to get answers about Keyboard backlight - ArchWiki
Without sensor and a software to run with it … how would be automatic? Without it just write a script/timer to run at certain hours.