Codeigniter 4 - How to connect to two or multiple databases

Hello
searching on the forum I have found only two really old topics (2007 and 2008) about how to connect to two or more databases
the manual is also a bit cryptic
https://codeigniter.com/user_guide/datab...-databases
because it doesn't detail about if just and only the .env file has to be edited or just and only the app/Config/Database.php has to be edited
... or if they should be edited BOTH accordingly
(well it really tells nothing, since the manual here looks conceived for gurus )

I suppose that thing with current Codeigniter 4 could be slightly changed

so, accordingly to this forum section title , thank you in advance for sharing the best practice for configuring the connection to two databases in Codeigniter 4