Bricks Query Loop popup does not have a control for setting the number of posts to be output when the query type is a non-standard one like ACF Repeater, ACF Relationship, Meta Box Relationship.
Customizing ACF Repeater/Relationship or Meta Box Relationship Query Parameters in Bricks
For query types other than post, term and user in Bricks i.e, ACF Repeater/ACF Relationship/Meta Box Relationship there are no built-in controls for modifying the…