In Preview, using the lasso, can I crop freestyle shapes with STRAIGHT lines?

I wanted to copy just part of a photo, but not in a square/rectangular shape. I wanted it shaped in a slightly foreshortened way. That is of course, to appear as a rectangle that is decreasing in size as it moves into the distance. My Preview app is nice, but I'd hoped to use the Adjust Size tool, in a way maybe relative to the option to adjust size disproportionally (like modifying from 4X6 to 5X8) but NOT with right angled corners. Not finding that option there, I thought I could crop that tapered shape with the lasso. So far the only option I see, to get real straight lines is to crop the photo 1 or two times > when lasso is dragged around most of an area, and the cursor is released, the two ends of the dragged line are connected automatically with a straight line. As seen here:

Crop once here, then re-crop to taper the left side next. The final image would be like a black walkway heading away, toward the horizon. Is there any simpler way, w/o buying another app?