AFAIK that firmware update isn't up yet, and won't be for weeks.
There was an update that made a small improvement in idle temp. https://www.cnx-software.com/2019/06/29/new-raspberry-pi-4-v...
There was an update that made a small improvement in idle temp. https://www.cnx-software.com/2019/06/29/new-raspberry-pi-4-v...