This is a head scratcher… On my system I can get the huge icons by scaling the Windows 10 mouse settings, then start Sketchup. To reset the mouse cursor to normal, I have to restart Sketchup for the new settings to take effect.
Assuming this happens to you regardless of Windows mouse settings, it seems this has been an issue for others as well, but I don’t see a conclusive resolution for this problem.
I noticed others with the problem also have x1440 displays… can you experiment with a standard display setting like 1920x1080 and see if the problem persists? Also if you have mulitpe monitors, try just one at a time to see if that has any effect.
If that does not show any results, consider re-installing SU and make sure you right click and “Run as Administrator”
If you figure it out, please post your solution to help others experiencing the same issue.