Please go to Settings > Permalinks. Have a look at the Permalinks page for other possibilities.
For You I think you need to use:
/%category%/%postname%
Hope this help!
UPDATE :
For additional slug based on category :
add_filter( 'post_link', 'custom_permalink', 10, 3 );
function custom_permalink( $permalink, $post, $leavename ) {
// Get the categories for the post
$category = get_the_category($post->ID);
if ( !empty($category) && $category[0]->cat_name == "news" ) {
$permalink = trailingslashit( home_url('news/'. $post->post_name ."https://wordpress.stackexchange.com/" ) );
}
return $permalink;
}
Please adjust above code according to requirements for more details please follow this answer or this page