Is this a WORDPRESS customized theme?

how about you email the author of the site?

When you check teh source you’ll see a lot of /wp-content/
And if that doesn’t ring a bell, then maybe this will look familiar: https://www.xxlmag.com/online/wp-login.php

Any website can be a WordPress theme, really. When you come down to it, the end result of a WP theme is (X)HTML code, just like any other website.

It makes more sense with certain styles, but anything’s possible.