This is a known limitation at this moment. I have passed a message to my colleages at MathWorks and this feature is under consideration for future releases.
In the meantime, below are some workarounds to re-size the icons in RoadRunner
- Increase the windows scaling in the display settings on the monitor in use
- Undock a pane and re-size it in another monitor or your laptop https://www.mathworks.com/help/roadrunner/ug/window-layouts.html#mw_735226f5-2114-43e8-908d-586ffc63ff94
