✅ Microsoft Graph API

var scopes = new[] { "https://graph.microsoft.com/.default" };

// Multi-tenant apps can use "common",
// single-tenant apps must use the tenant ID from the Azure portal
var tenantId = "teanantid";

// Values from app registration
var clientId = "clientid";
var clientSecret = "clientsecret";

// using Azure.Identity;
var options = new TokenCredentialOptions
{
    AuthorityHost = AzureAuthorityHosts.AzurePublicCloud
};

// https://learn.microsoft.com/dotnet/api/azure.identity.clientsecretcredential
var clientSecretCredential = new ClientSecretCredential(
    tenantId, clientId, clientSecret, options);

var graphClient = new GraphServiceClient(clientSecretCredential, scopes);


var x = await graphClient.Users["clientid"].Request().GetAsync();

Code: Authorization_RequestDenied
Message: Insufficient privileges to complete the operation.