Database-sample.php

Hmmm - isn't application/config/database.php pretty much what you described?
And the user guide (https://www.codeigniter.com/user_guide/d...ation.html) goes into more details.

As it is, you only need to create an environment-specific folder underneath aplicaiton/config, and copy then tailor any config files (eg database). You might have to make sure to git ignore them.

We have done this with CodeIgniter 4, with sample files to customize (.env, phpunit.xml.dit, Vagrantfile.dist), with the tailored files already git ignored.