How about iOS 12:00
Can you help me update it?
iPhone 6, iOS 12
Question marked as
An iPhone 5S 6/6plus can't be updated beyond 12.5.6, it doesn't have the hardware needed to run anything higher.
If you need a higher iOS version, you will have to purchase a newer phone.
If you're still on iOS 12 -
Go to Settings > General > Software Update.
This link will show you how to update your iPhone, iPad, or iPod touch using WiFi -
Update your iPhone or iPad - Apple Support
This link will show you how to update using your computer -
Update iOS on iPhone - Apple Support