CreateWellKnownSid

[DllImport("Advapi32.dll", SetLastError = true)][return: MarshalAs(UnmanagedType.Bool)]
public static extern bool CreateWellKnownSid(
   WELL_KNOWN_SID_TYPE WellKnownSidType,
   IntPtr DomainSid,
   IntPtr pSid,
   ref uint cbSid
);

Microsoft documentation: Link