OleCreate

[DllImport("ole32.dll", SetLastError = true)]
public static extern int OleCreate(
   Guid rclsid,
   Guid riid,
   uint renderopt,
   ref FORMATETC pFormatEtc,
   IOleClientSite pClientSite,
   IStorage pStg,
   out object ppvObj
);

Microsoft documentation: Link