Where is my app installed?

After installing PostgreSQL on my Debian-12 machine, I typed 'postgres --version' and got this msg:
bash: postgres: command not found

'psql --version', however, does work and gives me this message :

psql (PostgreSQL) 16.3 (Debian 16.3-1.pgdg120+1)

Obviously postgres is not in the path, but I don't know where the 'apt-get' installed it or why it did not add it to the path.

Is there a way I can locate the installation directory?

Thank in advance.