If the upgrade is being performed from OES 2018SP1 or below:
To update the Domain Functional Level: Re-run the script /opt/novell/xad/sbin/domainUpgrade.pl -D on the Primary Domain Controller of each domain.
To update the Forest Functional Level: Re-run the script /opt/novell/xad/sbin/domainUpgrade.pl -F on the Primary Domain Controller of Forest Root Domain.
If the upgrade is being done from OES 2018SP2 level, there is no need to run domainUpgrade.pl with above mentioned options as there is no functional level change in OES 2018SP2 and OES 2018SP3. The DS-Behavior-Version remains same as 7.