Hiya,
Per the configuration reference, you can set FUSIONAUTH_ADDITIONAL_JAVA_ARGS for
Any additional arguments that you want to pass to the Java VM where this service will run.
https://fusionauth.io/docs/v1/tech/reference/configuration#environment-variables
I know this was used to tweak proxy settings here: https://fusionauth.io/community/forum/topic/76/can-i-use-a-proxy-with-fusionauth
I'm not sure how to tweak the logging settings via java arguments, but maybe that gives you a place to start?