OleGetIconOfClass

[DllImport("ole32.dll", SetLastError = true)]
public static extern int OleGetIconOfClass(
   ref Guid rclsid,
   [MarshalAs(UnmanagedType.LPWStr)] string lpszLabel,
   [MarshalAs(UnmanagedType.Bool)] bool fUseTypeAsLabel,
   out IntPtr phicon
);

Microsoft documentation: Link