require_once() if a product in woocommerce incorporates a tag

I attempt to require_once() a file, if the situation of a selected tag is met, on a woocommerce single product web page.

I’ve added following to my capabilities.php

if(has_term('xyz', 'product_tag')){
    require_once WP_CONTENT_DIR . '/path/file.php';
}

It would not load my file, but when I take it out of my situation, it does load.

What can I do to attain this logic?