Hi @testuser7-8288,
Yes, Administrator can reset the password of end user from Azure AD Portal and that will be written back to On-premises Active Directory as well. This will also select the "User must change password at next logon" in properties of the user account in On-premises AD.
However, if you have selected "Password never expire" checkbox for the user, in that case "User must change password at next logon" won't get selected.
Administrators can also use below graph call for this purpose:
Call: POST https://graph.microsoft.com/beta/users/user's_object_id/authentication/passwordMethods/password_method_id/resetPassword
Body: {"newPassword":"P@$$w0rd","forceChangePasswordNextSignIn":true}
You can get password_method_id by using below call:
GET https://graph.microsoft.com/beta/users/user's_object_id/authentication/passwordMethods
Read more about these graph calls here: https://learn.microsoft.com/en-us/graph/api/passwordauthenticationmethod-resetpassword?view=graph-rest-beta&tabs=http
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