How to update my iPhone to latest version?

You can update an iPhone 7 as far as the latest release of iOS 15. Currently that is iOS 15.8.2.

Update your iPhone or iPad - Apple Support

You cannot update an iPhone 7 to iOS 16 or later.

iOS 16 and iPadOS 16 are compatible with these devices - Apple Support

Notice how the iPhone 7 is not in that list.

How do I update my iPhone to 14.1.4vesion

No Apple device can be updated to iOS 14.1.4. The maximum version will depend on your device, but you have not provided that information.

How to update a 6s plus

Binmusa wrote:

How to update a 6s plus

Have you read the reply posted above? If so, what issues are you facing that are not covered by the included information?