Agregar slug "blog" en articulos WordPress

add-blog-slug-posts-wordpress.php

<?php // No copiar esta línea

add_action('generate_rewrite_rules', 'dcms_posts_add_rewrite_rules');
function dcms_posts_add_rewrite_rules( $wp_rewrite ){
	$slug = "blog";
    $new_rules = [
        $slug.'/page/([0-9]{1,})/?$' => 'index.php?post_type=post&paged='. $wp_rewrite->preg_index(1),
        $slug.'/(.+?)/?$' => 'index.php?post_type=post&name='. $wp_rewrite->preg_index(1),
    ];
    $wp_rewrite->rules = $new_rules + $wp_rewrite->rules;
    return $wp_rewrite->rules;
}

add_filter('post_link', 'dcms_posts_change_blog_links', 1, 3);
function dcms_posts_change_blog_links($post_link, $id=0){
	$slug = "blog";
    $post = get_post($id);
    if( is_object($post) && $post->post_type == 'post'){
        return home_url('/'.$slug.'/'. $post->post_name.'/');
    }
    return $post_link;
}

Ref: https://stackoverflow.com/questions/21298149/how-to-add-blog-directory-in-front-of-single-wordpress-post