I assume that you are talking about post meta– data stored in the $wpdb->postmeta
table when you talk about “meta data fields”. The data in that table is associated with particular posts, of whatever type. It is not in any way keyed directly to the post type itself. There would be no way to connect a meta data field with a post type except by JOIN
ing on the $wpdb->posts
table based on the post ID and checking the post_type
for that post ID.
You can’t have meta data associated with a post type without having posts in that post type.
The only way I could see around that is if your theme has hard-coded post type meta data or stores that date somewhere else– the $wpdb->options
table perhaps– or if maybe the meta data keys are in some way identifiable by name– say books_cpt_author
for a books
post type. If that is the case, how you would get that information depends on how the theme has created/stored the data, and your question doesn’t contain enough information to guess at that.