According to Apple,
zsh (Z shell) is the default shell for all newly created user accounts, starting with macOS Catalina.
So you should verify your default shell with the command:
$ echo $SHELL
If the result is /bin/bash your default shell is BASH, and if the result is /bin/zsh the default is ZSH.
Go to home with $ cd ~/
and create the profile (if it does not exist) and edit it with the commands:
For bash:
$ touch .bash_profile
$ open .bash_profile
For ZSH:
$ touch .zprofile
$ open .zprofile