Which native method I can use to publish the WordPress custom post type post programmatically
You can use wp_insert_post to insert and publish the WordPress custom post type post programmatically
$post_id = wp_insert_post(array ( 'post_type' => 'post_type', 'post_title' => $title, 'post_content' => $content, 'post_status' => 'publish', 'comment_status' => 'closed', 'ping_status' => 'closed', ));