Here you can set the so-called Default template.
The default template is used as the template for OG and Twitter card images for all your post types and static pages.
You should always have the Default template set to one of the available templates.
If you wish to override the default template on the level of the specific post type, you can certainly do so.
In the Post types section, you will notice that all the post types available in your WordPress instance are listed.
Feel free to override the default template for the desired custom post types. The posts belonging to that post type will use the set template instead of the default one.
By choosing No images by OpenGraphiq, you can disable the OpenGraphiq functionality for that specific Post Type