Assign a group to a Intune Endpoint security policy

I'd like to find a way using PowerShell to assign a group to a Intune endpoint security policy like disk encryption or a security baseline for Windows 10 (not iOS or Android). I managed to create policies using PS but can't find how to assign a group.

I used the Graph API to create the policy using https://graph.microsoft.com/beta/deviceManagement/templates/$TemplateId/createInstance.

Any help would be appreciated.

Cheers