Hi Peter,
I'm not aware of any option to do so.
The Route Profile Tool allows you to play with some settings, but from what I know, you can only increase the interval, not decrease it.
In this example, you see on the Route Profile Tool, on the right side of your screen, that the minimum elevation interval is 90. It can be increased to 450, but not decreased back to 30 like it used to be several years ago.
I'm not sure if other settings of the Route Profile can help you with the detailed elevation profile you're looking for.
Best regards,
Julien