Hi,
I think the Gcode that results from reading a string is just a series of Ascii characters, they do not have a font size.
It is only when the string is displayed that those characters get fleshed out into screen readable symbols.....and the size of each symbol is a property
of the display Window, not the character string itself.
May I suggest you alter the properties of the Gcode window in Mach to have the font size of your choice.
Craig