Relevant: Correct way to use Selection (Lasso, Box) on an Image - #7 by Bryan
Additional question regarding your use case: 1) Do you just want the xy coords of an arbitrarily drawn box, or do you need the image “pixel” values contained in that selection?
Former would be pretty trivial with the draw tools, latter more complicated as you’d need to slice and dice a 2d array (as that’s how the image pixels are stored).