We generally try not to log secrets at any logging level so this wouldn’t help here.
You can actually change the logging level via logback.xml files, see Chapter 3: Configuration for some general documentation on that and How can I make debug statements visible in the sandbox logs? - #2 by cocreature for some of the pitfalls if you try to configure the logback file and run it via assistant. That said, our docs here are sorely lacking and I think a --log-level flag is probably a good idea anyway.