Other Intune-related topics, including unsupported scenarios and platform-specific behaviors
@Barak Peley Thanks for posting in our Q&A.
Based on my research, I didn't find such graph API. However, there is a built-in setting can designate or remove a user as an admin in intune. It is not needed to upload an XML file. Please Select Endpoint security > Account protection. Select Create Policy and choose Windows 10 and later as the platform and Local user group membership. For more details, please refer to the following article:
Hope it will give you some ideas.
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