Being a Novice to Libre Office could you please help in providing the information below.
Is the Log4j CVE-2021-44228 vulnerability applicable to Libre Office 6.4.7.2?
LibreOffice is safe. If it were vulnerable, it could only be threatened by a specially made document with inbuilt code that requires Java to run.
Source: A malicious document could lead to RCE in Apache OpenOffice (CVE-2021-33035) - Help Net Security
HSQL has the required interface to log database events with the help of log4j. But if you really wanted that, you would have to install and configure log4j.
Note that LibreOffice does not have that vulnerability either.