It's a common practice to debug PHP script using Xdebug. Xdebug is an extension for PHP to assist with debugging and development.

Please check my post below for detailed steps. In this article, I'm going to introduce a more convenient way to fast setup development environment with PHPStorm, Docker, Docker compose and Xdebug.

https://dzone.com/articles/setup-wordpress-debug-environment-with-docker-and