Auto Zoom, as I interpret it is that iFly will automatically zoom out to show either the whole route, or some large portion of it, then as we approach the landing airport, it will automatically zoom in keeping the landing airport within view. I have a very old Lowrance 1000 that does this.
Having said that, I could imagine that, since we have ADS-B traffic/weather, we may want to change that behavior a bit.
On departure, and within the airport area, keep the zoom close enough to be able to see whatever traffic there is. Then, once outside the airport area, it would zoom out to our selected max zoom range.
Enroute, it might also auto zoom in if we get within a certain distance/altitude of Class C, B, or D airspaces, then return once we're out of those areas.
Have a user selectable maximum zoom distance (if I leave NY for CA, I probably don't need to see the entire country), so that I can see a reasonable distance ahead, then as I approach the landing airport, it would zoom in to keep just the airport and aircraft depicted in the entire screen.