update post meta

add_action('wp_head',function() {
    $cat_name = 'Gaming';
    $category = get_term_by('name', $cat_name, 'category');
    $args = array(
        'post_type' => 'post',
        'tax_query' => array(
            array(
                'taxonomy' => 'category',
                'field' => 'term_id',
                'terms' => $category->term_id,
            )
        )
    );
    $query = new WP_Query( $args );
    foreach ($query->posts as $post) {
        update_post_meta($post->ID, 'jnews_post_split', [
            'enable_post_split' => '1',
            'post_split' => [
                [
                    'template' => '6',
                    'tag' => 'h2',
                    'numbering' => 'asc',
                    'mode' => 'normal',
                    'first' => '0',
                    'enable_toc' => '1',
                    'toc_type' => 'both',
                ],
            ],
        ]);
    }
});