Oracle Solaris 11.4 SU33 is the minimum software version required for Oracle SPARC servers.
To update the Solaris OS image on a SPARC system, use the Oracle Solaris 11.4 Image Packing System . For more details. see Adding and Updating Software in Oracle® Solaris 11.4 (https://docs.oracle.com/cd/E53394_01/html/E54739/index.html)