Changing Users' UPN

We have a situation with a tenant with cloud-only users which are using office apps logging with their UPN like email address removed for privacy reasons.

Now the tenant is being synchronized with AD and the users being "soft matched".
To do the soft match we must change the "cloud" UPN to match the AD's and that force the users to logoff from the office apps and re-login with the new UPN.

Is there a way to avoid that or automate it ?

thanks

SC