Yes. New boards can be created within a project for the purpose of instantly working in small sub-teams with private, “eyes-only” content. Boards can be created, and members – either existing project members or members outside the project – can be invited to that board only for visibility and collaboration around its content. Only those invited to that board will have visibility to its content.
The project owner is not notified when a new board/sub-team is created, and would only see the new board and its content if he/she were invited to the board as a member.
The project owner, noted at the bottom of the project, and all invited members to a project, have the ability to create boards.