Portrait photo can be both: persons in their own environment, spontaneous, life-like ...
... or Studio Portrait either with an interaction among photographer and subject, or the photographer hiding in its invisibility behind the camera.
For certain portraits in Studio, I shoot two images only, in 4x5" b/w plates, different positions, in a quest for perfection.
Artistic power of the view-camera?
I love this shot takeng after a long day's photo shooting