How do I update my iPhone 7 to iOS 14?

To update to the most recent, compatible version of iOS, please see: Update your iPhone, iPad, or iPod touch - Apple Support

And: If your iPhone, iPad, or iPod touch won't update - Apple Support

If the above Apple articles do not help, please post back with relevant information. 

NOTE: No Apple device can be updated to iOS 14.

iOS 14 is not available for any phone at this time. What phone do you have and what is the current iOS version?

Go to settings - general - software update and start there.

I phone 7