Security Keys for your Apple Account is an optional security feature designed for people (such as celebrities, journalists, and members of government) who want extra protection from targeted attacks on their account, including phishing and social engineering scams.
A security key is a small third-party hardware device that you can connect to your iPad and use to verify your identity when signing in to your Apple Account. The physical key replaces the six-digit verification codes normally used in two-factor authentication, which keeps this information from being intercepted or requested by an attacker.
For details about security key requirements, see the Apple Support article > [your name] > Sign-In & Security.
Tap Unlock Account, then follow the onscreen instructions to unlock your Apple Account.
If you think your account might have been locked because someone else knows your password, tap Change Password and enter a new one.
Tap Done.
You can pair up to six security keys with your Apple Account. If you reach the limit and need to pair additional keys, you can remove one or more of your paired keys. You can replace keys you’ve removed at any time.
Go to Settings Keep your Apple Account secure on iPad