要设置新帖子的默认值，可以尝试以下代码：

$postType = "product";

add_action("save_post_" . $postType, function ($post_ID, \\WP_Post $post, $update) {

    if (!$update) {

        // default values for new products

        update_post_meta($post->ID, "_manage_stock", "yes");
        update_post_meta($post->ID, "_stock", 1);


        return;

    }


    // here, operations for updated products


}, 10, 3);