PostgreSQL - How to login with my Linux user account - Mailing list pgsql-general

I'd like to log into my newly installed PostgreSQL [ PostgreSQL 12.15 (Debian 12.15-1.pgdg120+1) ] using my linux account.
In trying to do that this web page suggest that I enter :

psql -d mydb -U myuser -W

However, that command requires a database_name (mydb), and PosgreSQL 12.15 being so freshly installed does not yet 
have any database created by me.

How would you suggest I circumvent this challenge?

Mind you that, using the postgres account I have created other accounts.


Role name |                         Attributes                         | Member of 
-----------+------------------------------------------------------------+----------- chispa    | Superuser                                                  | {} pedro     | Superuser                                                  | {} postgres  | Superuser, Create role, Create DB, Replication, Bypass RLS | {}

Thanks in advance.