A lot of websites are offering dark mode as to not blast their users with blue light destroying their ability to fall asleep.
It would be valuable to have a option in the template settings to have a toggle switch to enable a dark/day icon in the header, and also have the option to have it auto switch based on the daylight hours of the the user based on their IP address.
Also, it should have a CSS pallet of colors for customization.
This would be a realtively small feature addition that would provide a lot of value to millions of people.