I'm trying to think of an intuitive way to make the the start/end dates changeable for the timeline (x-axis) of this graph.
On mobile this would be easy because you could use pinch to zoom in/out but is there a good way to do it on desktop?
If you want to zoom on a particular range, but still see underlying trends you can use a timeline scrubber below the x-axis.
Highcharts is a well known library that has this component. You can zoom using direct manipulation, and you can see a macro view of trend volume outside of the zoom window at the same time.
Highcharts refers to this as a scrollbar in their documentation.