Not sure what you are expecting to be an editable page, and how you are expecting to see it in this case. If you are using a browser, then you only see the rendered output from the PHP file. To edit the pages you would need an editor, like VS Code.
My xampp/php/pear directory contains PHP files and folders. The php files are editable, but I don't think you should be editing those, as they relate to content installed by XAMPP itself. While I guess you could edit them, it is likely not a good idea. You content should really be under the xampp/htdocs folder.
With XAMPP, or more specifically, PHP, editable pages are files with extensions like .php, .html, .css, and such.
Information on the PHP get_include_path() function can be obtained here
https://www.php.net/manual/en/function. ... e-path.php. Basically, though, the get_include_path() function returns the php.ini configuration value from the php.ini configuration file. That file is more about overall PHP configuration. I believe this is different from what you are tasked with doing.
Including files in your PHP code is accomplished with the PHP include and require statements. These would be used in your index.php, or other php files for your site. You can see an example on
https://www.w3schools.com/PHP/php_includes.asp or read about the statements on the PHP site here
https://www.php.net/manual/en/function.include.php, and here
https://www.php.net/manual/en/function.require.php.