Guru, most other icons do indeed grow larger and look normal, even at 300%.
However, for some programs (such as Adobe) I had to follow the advice found here: https://www.danantonielli.com/adobe-app-scaling-on-high-dpi-displays-fix/
I was able to find the application file (in the file containing the program), copy it and create a *.manifest file, as Dan Antonielli explains on his website. The manifest file was then placed in the program folder. That worked beautifully on a number of programs where, when the program was opened, what popped up was so tiny it was unusable. When the program was restarted, the icon was resized perfectly.
I am a musician and I use Finale for composing music. The manifest file fix worked on that, as well.
Perhaps it would work for this, too -- but I don't know what file controls this icon. Here's a screen shot so you can see exactly what I'm dealing with: