In a pack-based installation, use the following command
openproject logs --tail
To modify the log level, use the following. You must restart OpenProject to apply your changes (systemctl restart openproject.service).
Use one of [debug | info | warn | error] (default is info)
openproject config:set OPENPROJECT_LOG__LEVEL="debug"
To set logging back to the default, simply unset the variable
openproject config:unset OPENPROJECT_LOG__LEVEL