It is important to note that you do not want to lose your security key. Apple will prompt you to set up two first, so you can keep a backup in a safe place. But if you somehow get both of them wrong, there’s a chance you’ll be permanently locked out of your account (there may be recovery options, but Apple isn’t specifying what they are, possibly for reasons security).
You also need to follow this process when logging into your Apple ID in a new web browser, and there are some places where it won’t work (at least not yet). Perhaps the most important is iCloud for Windows, so you might want to hold off if you use your Apple account on Windows devices. And you can’t use security keys with Apple devices running older software or with Apple IDs assigned to children.
Setting Security Keys
The first step is to buy a few security keys, which cost about $50 each online. Apple says you need certified keys to work with the FIDO (Fast ID Online) standard, and the right connections for your devices: NFC (iPhones) only, lightning, USB-C, or USB-A. It is fine to use adapter dongles and cables with these security keys, it should be easier to find keys that work across everything you are going to use.
With your physical keys in hand and the latest software updates installed, you can set everything up from your iPhone or iPad by going to Settings, tapping your name at the top, and choosing Password & Security. Choose Add Security Keys guide you through the process of associating them with your Apple ID. At the same time, you can review all the devices currently linked to your Apple ID.
On macOS, make sure you’re running the latest software, then open the Apple menu and select System Settings. Click your name at the top of the left navigation pane, then select Password & Security and click Add next to the Security Keys heading. You’ll then be taken through the steps needed to link your keys to your account, and you’ll be shown the devices you’re already using with your Apple ID.
You must add at least two security keys to your account, as mentioned earlier, and you can add up to six. Go to the same screens on iOS, iPadOS, or macOS if you want to delete one or more of your security keys – you’ll see a Remove All Security Keys option. If you select this, the two-factor authentication process will revert to using the passcode method, as it did before.