Want to add alias pages in hreflang tag

Using Concrete / Help
1

Dear all,
I’m using C5 version 8.5.5 with PHP 7.3.33 and have implemented hreflang tag via /application/config/site.php.
I want all the alias pages to be added as an alternate URL.

I’m using the following code:

<?php
return [
    'sites' => [
        'default' => [
            'multilingual' => [
                'set_alternate_hreflang' => true,
            ],
        ],
    ],
];

Can anyone help me to add alias pages as alternate urls.

Thanks in advance.