Generally no; a Canadian citizen may seek TN admission directly using the required documentation without first obtaining a TN visa. This is a general pattern, not a guarantee for every circumstance, so confirm it against current guidance and the applicant's own history.
Confirm the general rule fits this specific case
Prior immigration history, current location, or unusual employer circumstances can affect how the admission process actually plays out. Get the employer's letter and supporting documentation ready well before the planned entry, since presenting the case clearly at the time of entry matters more than it would for a visa application handled in advance. Treat any doubt about the applicant's history as worth resolving before travel.
Resolve the applicant's own history before booking travel, because the general rule that a Canadian citizen may seek TN admission directly without a visa is a pattern rather than a guarantee for every circumstance. Prior refusals, an earlier overstay, a withdrawn application, or an unusual employer arrangement can each change how the process actually unfolds, and the counter is the worst place to discover it. Have the employer letter and supporting documentation complete well before the planned entry, since presenting the case clearly at the moment of entry matters more here than where a visa application is handled in advance.
Treat any doubt as worth resolving first, and confirm the position against current official guidance.