When I open your own image, your submenu seems usable with my screen (43" 4k). But in your case, 150% is the maximum of SynthV. There is another way with your screen settings. In Windows, there is a screen scaling setting that you can also update (eg: 125% to 150%, etc.).
Small yes but definitely usable on my side (with your picture). But with more testing I find that the scale ratio between synthV and DAW does not seem to be 1 to 1. I had not noticed this before. It does not make a big difference to me but it is noticeable on my screen.
When I set my scale screen to 125%, I have to set SynthV to 150% to have an equivalent font size. So a screen is already at 150%, we cannot increase SynthV to 175% (not available).
There is also another setting (because you are talking about ARA), at the DAW level. With Cubase, in the preferences there is a scale setting (+25%…) that could also have an impact on the behavior of SynthV. Maybe the SynthV version 2 will be able to improve this problem.