How to make a php link in wordpress?

Hello, I am trying to make a dynamic(?) php link in my footer to an “about” page in php. Instead of using the page addition part of WordPress, I would like to make my own page in php that will always sit in the theme folder. It will be the about page, but I do not know how to link to that about page in the footer?

I’ve tried this piece of code below but it hasn’t worked. It just sais “page not found”. Could anyone help me please?

a href=”<?php echo get_settings(‘home’); ?>/about.php”>About</a