You can update your iPhone to the latest version of iOS when they become available and your software is compatible with it. The iPhone 6 is compatible with iOS 14 and as such can be updated to it.
How Can I Update My iPhone 6 To iOS 14?
To update your iPhone 6 wirelessly, follow the steps below:
First Back up your device using iCloud or your computer. Then Plug your device on charge and connect to the internet with Wi-Fi.
After that, proceed to Settings then tap on General, then tap Software Update. If you happen to see two software update options available, choose the one that you prefer to install and tap Install Now.
Again, if you see Download and Install instead, tap it to download the update, enter your passcode, then tap Install Now. If a message asks to temporarily remove apps for more space for the update, tap Continue to allow apps to be removed. After installation is complete, those apps will automatically be reinstalled.
However, if you tap Cancel instead, you can delete content manually from your device to add more space.
Additionally, you can customize your updates to allow your device to auto-update while you sleep.
Go to Settings, then General, then Software Update.
Tap Automatic Updates, then turn on Download iOS Updates. Also, turn on Install iOS Updates. Your device will automatically update to the latest version of iOS.