A vertical zoom feature is pretty much present in all the other vocal synth programs (even in DAWs) that I have used. I personally use it to have more precise tuning on the notes, which I think other people would also enjoy that feature. Vertical zoom is also an accessibility feature that could be more favorable than interface scaling, which confines the space of the other windows when the other panels are open, in which people usually leave a few of them open.
I do hope that this feature could be considered to further enhance the user experience of SynthV.