The following is an early version of SZUS2 written by me in junior high using PHP.
I also coded a PHP framework for this, it's called techplatform.
If you want a demo version of SZUS2, please visit https://demos2.dms-serwis.com.pl and follow the on-site instructions.
The only configuration baked into static files was the access to MySQL. Everything else was stored in the database proper.
Techplatform was an early attempt at a framework in PHP. It contained an ORM where you did define the models using XML which then compiled output files with a Python 2 tool.
It also contained a templating library, which is weird, because PHP is itself an overgrown templating system, basically.