How do I download the newest updated version to my phone? I want to be able to use my face identification

If you're seeing the message shown in the related article at the top of the page and updating doesn't work, you'll need to bring your device in for service as it's indicating a hardware issue.

have you read thru this support article for updating?

Update your iPhone, iPad, or iPod touch - Apple Support

need more storage for update?

If you need more space for an update on your iPhone, iPad, or iPod touch - Apple Support

issues?

Updating iOS: common issues and solutions - Apple Community

video..

Hello there !

if you have trouble with Face ID see this article:

If an alert says Face ID has been disabled on your iPhone or iPad Pro

if you want to update your iPhone

Update your iPhone, iPad, or iPod touch