On its own, usually not. Supervising non-professional, non-supervisory staff does not make someone a personnel manager for L-1A purposes. The stronger case is that she manages an essential function of the business at a senior level.
Count the function, not the heads
Hypothetical example: a Grand Bay-Westfield distributor drafts a petition describing its operations manager as supervising four drivers and one dispatcher at the U.S. depot. Read literally, that is first-line supervision of operational staff, which the L-1A managerial definition does not reach.
The same person, described accurately, controls fuel purchasing, carrier rate negotiation, delivery scheduling across a territory and the margin on every load, and she sets the policies that the depot runs on. That is a function-manager description, and it is supported by naming the function, showing it is essential to the company, showing she operates it at a senior level rather than performing the deliveries herself, and identifying who does the day-to-day work she directs. Rewriting the duty paragraph is not cosmetic here.
It changes which legal test the petition is asking the officer to apply.