This is another system administrative command that doesn’t really change from linux.
If you take a look at the command passwd, it doesn’t just change passwords. In fact, if you do:
passwd -e username
You will be shown the user’s current shell, and be asked for a new shell. Most people just use the default one for the system which usually is either ksh or bash, but to each their own on what you like. There are also ways to actually change the shell itself through the .profile upon login but that’s for another day.