Click the 3-lined Menu at the top-right of the VP window. Click VIEW and Show Dual Previews. 
Add the full-screen image to track 1.
Add the video to be zoomed on track 2.
Add the ZOOM effect and adjust it. If necessary, set the aspect ratio preset. Here it's a 4x3 video...
Click this image to enlarge it.
Next add the SCALE (Picture-In-Picture) effect and position the Base X and Y coordinates for a bottom-right window display.
P-in-P.mp4