Introduction
cPanel logs as well as Apache logs's rotation is handled by the cpanellogd service. While this log rotation daemon is not as configurable as rsyslog/logrotate, you are able to adjust the size threshold that cpanellogd uses before a log is rotated.
Procedure
To do so please navigate to:
WHM >> Server Configuration >> Tweak Settings >> Stats and Logs >> Log rotation size threshold
The default value is 300M, however, you may decrease this value if you want the logs to be rotate more often. Please note that this will take effect for all logs managed by cpanellogd.
For a full list of managed logs please refer to this article.