iPhone 13 Pro Max won't allow update to iOS 16

A question: 

1.

Do you have a MDM profile?

If so, contact your company - IT department.

2.

Have you install / use iOS Beta version?, if so remove the beta profile (Settings -> General -> VPN & Device Management).

Then Restart your iPhone and check for updates again.

You might have used an iOS beta version on your device. Should be this case, go to Settings>General>VPN & Profile management, delete the beta profile, restart your iPhone, check for updates availability again.

Shoudn't be this case, contact Apple Support directly, using this link:--> Get Support

Regards

Giulio