Create Silhouette Then Use as Clipping Mask

For hard, precise edges a vector-based shape used as a clipping mask would be the best approach. I'm not a big fan of auto-tracing pixel-based objects unless a "dirty" look with irregularities along the edges of the vector object is desired. It's not difficult to manually trace a silhouette of a person using the pen tool. The keyboard shortcuts in Photoshop and Illustrator both make the pen tool much easier to use (you can modify anchor points on the fly while the path is still being drawn).

Not everything featuring this kind of second story within a shape has hard edges all the way around. In those cases you'll need to use Photoshop-based tricks like alpha channel masks or layer blending tricks to accomplish the job.

Hi. You can draw the silhouette in Illustrator, then, import the image and create a mask with the silhouette. Or you can create the silhouette and the mask en Photoshop,

The silhouette can either be traced manually if the template image is not suitable for automatic procedures.

In case you have a high contrast image with white background (or background that can be isolated with channels in Photoshop), you can increase that contrast first in Photoshop and then autotrace your silhouette.

All of this requires some more than just superficial knowledge of image editing.

You might want to research how to use channels in Photoshop.

The documentation has all about  how to use the pen tool and pencil in Illustrator: How to draw with the Pen, Curvature, or Pencil tool in Illustrator