You can’t enqueue a php file normally as a stylesheet and have it work.
For example, this will not work
wp_enqueue_style('your-handle', 'your-file.php');
the reason for this is not that WP will not enqueue it or add it to your page. This issue is that no WP or plugin function will be available in this file.
Your 2 choices are to put the custom styles inline in the header of your page or to enqueue the style script using admin-ajax.php
