Custom base RSS feed for WordPress

Set UTC +3 time zone

<?php
header('Content-Type: application/rss+xml; charset=UTF-8');

echo '<?xml version="1.0" encoding="UTF-8" ?>';

?>
<rss version="2.0">
    <channel>
        <title><?php echo get_bloginfo('name'); ?></title>
        <link><?php echo get_bloginfo('url'); ?></link>
        <description>Your custom feed description</description>
        <language>en-us</language>

        <?php
        $args = array(
            'post_type' => 'post',  // Fetch posts or any custom post types
            'posts_per_page' => 10  // Limit the number of posts
        );
        $custom_query = new WP_Query($args);

        if ($custom_query->have_posts()):
            while ($custom_query->have_posts()):
                $custom_query->the_post();
                ?>
                <item>
                    <title><?php the_title_rss(); ?></title>
                    <link><?php the_permalink_rss(); ?></link>
                    <description><![CDATA[<?php the_excerpt_rss(); ?>]]></description>
                    <pubDate>
                        <?php echo date('D, d M Y H:i:s', strtotime(get_the_time('Y-m-d H:i:s') . ' +0 hours')) . ' +0300'; ?>
                    </pubDate>
                    <?php
                    // Get post categories
                    $categories = get_the_category();
                    if (!empty($categories)):
                        foreach ($categories as $category):
                            ?>
                            <category><?php echo $category->name; ?></category>
                            <?php
                        endforeach;
                    endif;
                    ?>
                    <full-text>
                        <![CDATA[
            <?php echo apply_filters('the_content', get_the_content()); ?>
        ]]>
                    </full-text>

                    <?php if (has_post_thumbnail()):
                        $thumbnail_url = get_the_post_thumbnail_url(get_the_ID(), 'full'); // Get the featured image URL
                        ?>
                        <enclosure url="<?php echo esc_url($thumbnail_url); ?>" type="image/jpeg" />
                    <?php endif; ?>
                    <guid isPermaLink="false"><?php the_guid(); ?></guid>
                </item>
                <?php
            endwhile;
        endif;
        wp_reset_postdata();
        ?>
    </channel>
</rss>

Creteate a new feed custom.pnpg file in the theme folder. function.php:

function custom_feed_init() {
    add_feed('custom', 'generate_custom_feed');
}
add_action('init', 'custom_feed_init');

function generate_custom_feed() {
    get_template_part('custom');
}

Change the feed URL

add_action('parse_request', function($wp) {
    if (isset($wp->query_vars['feed']) && isset($_GET['custom'])) {
        error_log('Custom feed hook triggered');
        load_template(get_template_directory() . '/custom.php');
        exit;
    }
});