CVar uiScale

This variable is used to scale the User Interface. You must have the variable useUiScale set to 1 for this variable to be of any effect.

In Config.wtf:
 * SET uiScale "1.0"

In Console:
 * /console uiscale 1.0

Acceptable values
 * 0.64 up to 8.0 and beyond
 * Values lower than 1.0 shrink the size interface. Values higher than 1.0 increase the size of the interface.
 * Values lower than 0.64 have no effect