org-tags-match-list-sublevels

org-tags-match-list-sublevels is a variable defined in `org.el'.
Its value is

t

Documentation:
Non-nil means list also sublevels of headlines matching a search.
This variable applies to tags/property searches, and also to stuck
projects because this search is based on a tags match as well.

When set to the symbol `indented', sublevels are indented with
leading dots.

Because of tag inheritance (see variable `org-use-tag-inheritance'),
the sublevels of a headline matching a tag search often also match
the same search. Listing all of them can create very long lists.
Setting this variable to nil causes subtrees of a match to be skipped.

This variable is semi-obsolete and probably should always be true. It
is better to limit inheritance to certain tags using the variables
`org-use-tag-inheritance' and `org-tags-exclude-from-inheritance'.

You can customize this variable.