ejofi said earlier, and this worked for me even though i am using proton to run it:
You can edit resolution multiplier manually in \AppData\Roaming\MSB\save.txt
I use xres=4 and yres=4. I think default multiplier was 2.
for future linux users looking for the file it should be in a really long steam app id in your home dir's .local steam (im on ubuntu) if you set it up as an app through steam (you should it makes the proton process and management process easy)