Redirect old Posts URL to new URL

There are lots of solutions to redirect from the old post URL to the new post URL.

1. You can install a plugin “Safe Redirect Manager” and set it from the admin panel.
2. You can write some snippet in the functions.php file as:

add_action('template_redirect', 'post_redirect_by_custom_filters');
function post_redirect_by_custom_filters() {
    global $post;
    // this array can contain category names, slugs or even IDs.
    $catArray = ['blog'];
    if (is_single($post->ID) && !has_category($catArray, $post)) {
        $new_url = "http://www.newurl.com/blog/{$post->post_name}/";  
        wp_redirect($new_url, 301);
        exit;
    }
}

For more details please follow the below link.

https://www.ryadel.com/en/wordpress-redirect-posts-categories-tags-custom-conditions-301-302/amp/