Notes
Controlling Access Using Hierarchies determines whether users have access to records they don’t own, including records to which they don’t have sharing access, but someone below them in the hierarchy does.
Beyond setting the organization-wide sharing defaults for each object, you can specify whether users have access to the data owned by or shared with their subordinates in the hierarchy.
For example, the role hierarchy automatically grants record access to users above the record owner in the hierarchy. By default, the Grant Access Using Hierarchies option is enabled for most standard objects, and it can only be changed for custom objects.