Sheriffs play a bit of a different role in the city, they're different from police, so being outnumbered by crims isn't really a concern, they deal with people who don't pay their fines, and manage security for the courts.
You can fill out an application to join here: https://forms.gle/ixMYpSyx6ZSajGtbA
If you're more interested in law enforcement, consider joining the new Corrections Department. You can apply for that here: https://bluebirdrp.live/index.php?/support/ just select the option for "BlueBirdRP Corrections Victoria Recruitment" and fill out the application there. Police applications are closed at the moment