Hi!
This is the most recent statement regarding JDK 16/17 that I could find: Will Java 16 and 17 be supported in SonarQube 8.9 LTS? - #2 by Michael
Unfortunately, and to answer explicitly your question: No, you won’t be able to have the support of Java 16 and Java 17 with SQ 8.9 LTS . Since SQ 7.9 LTS, versions of languages analyzers are sticked to SQ versions, and can not be independently updated.
Consequently, the only way to get access to the support of Java 16 and 17 before our next LTS is to rely on the latest releases of the SonarQube 9.X series.