An emailed code, then Face ID, Touch ID, Windows Hello or an authenticator app.
The first time, open the setup link we send you. You confirm your email with a code, then add a passkey (Face ID, Touch ID or Windows Hello) or an authenticator app. You also get recovery codes: keep them somewhere safe, offline.
After that, sign in with your email and your passkey. Lost your phone? Use a recovery code, then add your new phone. Sign out everywhere in Settings ends every session on every device.