Can’t update my iPhone6

On your device, tap:

Settings > General > Software Update.

1. If it says your device is up to date there is nothing more you can do. If apps you are trying to use say you need a higher iOS version, you will need to buy a newer device if you want to run those apps or features.

2. If it says an update is available you will only be given one update selection which will be the highest available iOS version supported by your device. Click on a link below for full instructions about how to update with wi-fi or 5G, or using a computer if you have storage or connectivity issues. If the update listed is not equal to or higher than the iOS version you need to use a feature, you again will need to buy newer equipment if you want to use that feature.

"Update your iPhone, iPad, or iPod touch" click here --> https://support.apple.com/HT204204

Or this video:

"How to update your iPhone or iPad" click here --> https://youtu.be/csJAEyvvruY

iPhone 6: You cannot update to iOS 14; you can update only to iOS 12.5.2