Stretching text area on pdf

Hi friends, I'm trying to stretch lecture slides. My lecturer hasn't exported their slides properly resulting in a very small area with the slide and the rest is blank. All I want to do is enlarge the slides to fill a quarter of the page each and essentially end up with four slides per page. When I crop all and drag, it doesn't enlarge the text. Is there a way to flatten? the slide and simply drag to enlarge whilst keeping the text searchable? Thanks in advance 🙂