Help me to change the font size of my POS Printer

Hello forum,
I have a TP-100 dotmatix pos printer and I'm curruntly print receipt using printer.print method. But when I try to change the font size using printer.fontsize, there is no effect on the print outs. I want to use different sizes of fonts in my POS printer. Is there any way I can do this without using Printer.FontSize.

I also want to know how to display line of text on a Pole Display. If theres anyone to help me that will be a great help. Thank You!