WordPress: Add Google News Sitemaps using WordPress SEO, for more explanation check the blog post: https://aalakkad.github.io/blog/wordpress-add-google-news-sitemaps/

functions.php

<?php
//////////////////////////////////////////////////////////////////////////////////
// Google News Sitemap                                                          //
//                                                                              //
// Refer to: https://aalakkad.github.io/blog/wordpress-add-google-news-sitemaps //
//////////////////////////////////////////////////////////////////////////////////

// Check for WPSEO_Sitemaps class from WordPress SEO plugin
if(class_exists('WPSEO_Sitemaps')) {
    add_action('init', 'my_custom_google_news_sitemap');

    function my_custom_google_news_sitemap() {
        $GLOBALS['wpseo_sitemaps']->register_sitemap( 'google-news-sitemap', function() {

            $query_args = [
                'post_type'      => 'post',
                'post_status'    => 'publish',
                'posts_per_page' => 1000, // Google bots won't crawl more than 1000 entries per sitemap
                'paged'          => 1
            ];

            $posts = get_posts($query_args);

            $site_title = get_bloginfo( 'name' ); // get site's name
            $language   = get_bloginfo( 'language' ); // get site's language (e.g. en or ar)

            $xml = '<?xml version="1.0" encoding="UTF-8"?>
            <urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9"
            xmlns:news="http://www.google.com/schemas/sitemap-news/0.9">';
            foreach($posts as $post) {
                $permalink = get_permalink($post->ID);

                $title    = $post->post_title;
                $date     = get_the_time( 'c', $post->ID ); // c is the complete date plus hours, minutes, seconds and a decimal fraction of a second which is accepted by Google
                $genres   = 'PressRelease'; // Comma-seperated geners
                $keywords = 'comma, seperated, keywords'; // Comma-seperated keywords

                $xml .= <<<XML
                <url>
                    <loc>{$permalink}</loc>
                    <news:news>
                      <news:publication>
                        <news:name>{$site_title}</news:name>
                        <news:language>{$language}</news:language>
                    </news:publication>
                    <news:genres>{$genres}</news:genres>
                    <news:publication_date>{$date}</news:publication_date>
                    <news:title>{$title}</news:title>
                    <news:keywords>{$keywords}</news:keywords>
                </news:news>
            </url>
XML;
            }
            $xml .= '</urlset>';

            echo $xml;

            // Remove any wp_footer actions and die()
            $GLOBALS['wpseo_sitemaps']->sitemap_close();
        }, 'sitemap_news\.xml');
    }
}