Yes, on Windows you can use this to trigger the weekly 200/RC2 behavior on any Otter build:
set QT_AUTO_SCREEN_SCALE_FACTOR=1
otter-browser
And like this for the reverse:
set QT_AUTO_SCREEN_SCALE_FACTOR=0
otter-browser
It might be possible to string it together in a shortcut without having to create a batch file or open a command prompt, but my CMD syntax knowledge is a little rusty. This might not work as written:
set QT_AUTO_SCREEN_SCALE_FACTOR=0 & otter-browser
Another option would be something like this. This might not work as written either:
cmd /c "set QT_AUTO_SCREEN_SCALE_FACTOR=0&&otter-browser"