Not by itself. The rule is about the nature of the duties, and a manager of an essential function can qualify without a large staff. A small team does raise the question of whether the person will mainly manage or mainly produce, which the petition must answer with specifics.
Function management is a real category with its own proof
USCIS recognizes two kinds of manager: one who manages people, usually professionals or other supervisors, and one who manages an essential function of the organization at a senior level. A Lac-Beauport transferee taking over a five-person U.S. office can fit either, but the evidence differs.
For a people manager, show that subordinates are professionals or supervisors and that the transferee hires, evaluates and directs them. For a function manager, show that the function is essential to the business, that the transferee sets its policy and priorities, and that lower-level staff or contractors carry out the routine work. What does not work is a description in which the transferee's own billable output is the office's main product.
The test also applies to the year abroad: the qualifying employment in Québec must itself have been managerial, executive or specialized-knowledge work, so an employee promoted into a director role only weeks before the petition may not have a qualifying year in the right capacity.