It seems that there is no way to zoom it. Why?
I believe now the more appropriate question is: When?
With the new graphing comes vector graphics for the graph I assume. Why they haven’t turned on the SVG output of matplotlib I do not know but maybe one of the devs can comment on that.
In the meantime I use the screen zoom feature of macOS to zoom in. Or you can use the zoom level in your browser. It ain’t pretty but for the time being…
Also you can manually zoom by adjusting the settings of the graph:
That’s a pretty good summary!
Don’t forget, you can go to https://road.beeminder.com/ and get an interactive zoomable graph.