DPI/Scaling configuration?

Every modern graphical linux distro has this as a GUI option.

So every modern graphical linux distro has it's own GUI implementation of it for FVWM? Or without sarcasm, it's a Window Manager problem in X, and my google-fu says FVWM doesn't support this feature.

FVWM is a an ultra minimal window manager favoring advanced users comfortable on a terminal. No major consumer focused distros ship with it.

Gnome or KDE are likely a better fit for someone that cannot scale DPI on a terminal.