Dark Mode one of the features that everyone needs on our phone no matter which phone you using right now iPhone or Android most android phone’s supported Dark mode which requires Android Pie at least for pixel and nonpixel phones also start supported
But
When it comes to An iPhone where’s which requires iOS 13 and later supports iPhone SE, 6S, and later iPhone’s but hopefully its good for many iOS users but really and the thing you need to know that older iPhone’s not supported yet but there is way to get it on older iPhone especially for iPhone 5s,6 iOS 12/12.5.7

What Dark Mode Do
Dark Mode is very essential when it comes to reducing eye strain to adjust screens with your light conditions even it also reduces the battery consumption as well to you experience in the dark mode most the apps adopt as Youtube & Facebook but the system-wide dark mode is not present on iPhone 5s,6 which I think it’s left out one of the essential features and must-have on it
Also Read, Jailbreak iOS 12.5.4 iPhone 5s,6
Can we able to enable Dark Mode on iPhone 5s,6
By default iOS 13 is somehow requires at least to use the dark mode on any iPhone however its available on most of the iPhones excluding the iPhone 5s,6 which runs now on iOS 12.5.4 which requires to have a jailbroken otherwise it impossible to enable the dark mode where’s most of us don’t want to do jailbreak if you want to latest feature’s of iOS it best to have the Latest iPhone
but
if you still want dark mode on your iPhone so
How to Get Dark Mode on My iPhone 5s,6
First, you need to Jailbreak your iPhone 5s,6
You need a Repo to add
Install the repo
Find Eclipse Dark mode
after all, you finally enabled the dark mode