Setting up and managing device configurations using Intune
@Venkata Srinivasa Kumar Barathula Thanks for posting in our Q&A. From your description, I know that you want to use getOmaSettingPlainTextValue function via Graph API, but it gets 403 forbidden error. If there is anything misunderstanding, feel free to let us know.
For this issue, it is suggested to try the following actions:
1.Please make sure that we add "DeviceManagementConfiguration.Read.All" and "DeviceManagementConfiguration.ReadWrite.All" in permissions of Graph.

2.Click on "F11" before we edit the OMA-URL settings. Then we will find the request URL about this custom profile. For example:

3.Please try to run the request URL in Graph and check if it is successful.
Hope it will help.
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