Currently, "Require re-register MFA" can only be set https://docs.microsoft.com/en-us/azure/active-directory/authentication/howto-mfa-userdevicesettings#manage-user-authentication-options, or via Pow...
This should be highest priority for Microsoft regardless of how many votes it gets here as MSOnline will stop working in October when basic authentication stops working leaving us with no alternative. between now and October Microsoft should have an alternative (such as Graph or V2 AzureAD module). We already updated all our scripts to Graph and V2 AzureAD commands using app registration. We're about 3 months away from the deadline and I'm not going to go back and use basic authentication in order to automate require re-registration for MFA. I'd rather not automate it temporarily and wait for Microsoft to provide a better alternative. Why isn't this a priority for Microsoft when they know the deadline is October is a mystery to me.