I have a line in my child theme as follows:
$bg_image = wp_get_attachment_url( get_post_meta(get_the_ID(), 'bg_image', true) );
It successfully provides me with the url of the image stored in the post meta, but what I would now like to do is specify a specific thumbnail size such as 'thumbnail' or 'medium'. The question was asked here but never answered.
Can anyone help?