I am running sonarqube on 8.9.8 version ,we cant do another upgrade any soon now.so wanted to know is there any option only to copy/upgrade latest rule sets on our current version running? is there any export /import option only for ruleset upgrades?
No. New language features / rulesets are only available in new SonarQube versions.
SonarQube v8.9.8 is EOL, which means it will receive no updates even if there is a vulnerability. It’s critical that you move to a supported version of SonarQube.