iPhone 6 doesn’t have dark mode option

Dark Mode was first introduced in iOS 13 and currently exists in iOS 15 and iOS 16.

Dark Mode feature does not exist in iOS 12 which you have installed on your iPhone 6.

You have an iPhone 6 and the iPhone 6 cannot be updated beyond iOS version 12. This is the reason there is no Dark Mode available for the iPhone 6. You will need a newer model iPhone to use higher versions of the iOS.

Axel F.

Because the dark mode option requires iOS 13, which in turn requires an iPhone 6S or newer.

Your iPhone 6 can only go as far as iOS 12.5.6.

Dark Mode requires iOS 13 or higher.