Not from within FileMaker. You're only option, as far as I know is to change your display settings in the operating system.
If you are using a Mac, option-cmd = and option-cmd - will zoom in and out (although the resolution suffers a bit). To toggle the zoom on and off use option-cmd 8.
Thanks. It took me a while to figure out.
First, Option_Cmd_8, to turn on zoom feature. (ALT_WIN_8 on PC keyboard)
Then, Option_Cmd_= (ALT_WIN_=) for zoom in.
or Option_Cmd_- (ALT_WIN_-) for zoom out.
The nice thing about the toggle is that you can set the zoom, toggle to normal view, and when you toggle back you have the same zoom setting.
I can live with the resolution degradation so I can live without a permanent squint.