No, sorry.
Think that would make sense only if there would be a regular tessellated mesh (as the default Plane object).
With the SELECT brush you can only select full triangles which are (fully) inside a certain brush radius.
If you need to select a certain shape (as a square) use the STAMP tool to draw the shape (this splits the triangles hit by its boundary) and select the resulting group by double click.
Gunter Weber
Triangle Artisan
Thanks, that closely addresses the issue I'm facing. Now down the rabbit hole of shape select ...