Pointing straight down you can zoom in/out and read it. It zooms rather quickly so it is hard to hit your exact number.
I find it easier to go to a fairly oblique view and zoom from there. The absolute rate of change in zoom is the same but since your POV is sliding along slantrange the vertical rate of change is lower. It is easier to get within say, six feet or so of desired value.
After that if you want to go back to vertical you can and should remain at that height. The one caveat is that when zooming in oblique you do traverse across the ground, so if you want to be looking at, say, San Francisco, start at some point well south of there, pointed north and do the zoom. The adjustment might leave you in the general area you want. After that just scroll to your target.
Happiness is not seeing another trite Ste. Maarten photo all week long.