You cannot, as there is no possibility to create custom roles that can feature such permissions, currently. And yes, it's unfortunate that you cannot go granular, it's a common feedback for the Graph folks at Microsoft.
Changing password of accounts with privileged roles with a Service Principal
Hello, Our IAM platform offers our users to change their Azure account password. Our platform uses the C# Graph SDK in order to change the password by authentication using a Service Principal. However, for certain accounts, the action fails with:
Microsoft.Graph.ServiceException: Code: Authorization_RequestDeniedMessage: Insufficient privileges to complete the operation.
Upon finding this page, I realize that our Service Principal would require "Privileged Authentication Administrator" if we would want to be able to change the password of any account in the directory. I am taking a chance here to ask you if there is a possibility to use a custom role instead as "Privileged Authentication Administator" would allow our Service Principal to do more than we would like. Or should I be considering a different approach? Thank you for your time.