AirTag cannot be used without two-factor authentication.
You can no longer disable two-factor authentication if you currently use it. Certain features in the most recent versions of iOS and macOS require this additional degree of protection, which is intended to secure your data. However, if you just modified your account, you can unenroll for two weeks. To restore to your old security settings, simply open your enrollment confirmation email and click the link. Remember that this makes your account less safe and prevents you from using features that require a higher degree of protection.