If you need to provide higher security for authentication, you should think about implementing Azure Multi-Factor Authentication. This provides a second factor (SMS, call, or authenticator app) for a successful authentication:

As you can see, today this feature is still available only with the Azure Classic portal and looks as follows:

After you choose CREATE A NEW MULTI-FACTOR AUTHENTICATION PROVIDER, the GUI looks as follows:

As you can see, you will have to pay for multi-factor authentication for Per Authentication or Per User:

Now you can start managing multi-factor authentication Per User in the dedicated MFA portal:

Keep in mind that MFA is not supported during the setup process of Azure Stack for the user part. You will need to enable a bypass during the installation. After the installation is finished, you should enable it again.