Is it possible to modify the following xml snippet to give different sizes to the dollar sign and the value?

I tried inserting C#-style parameters, like {0} and {1} where {0} is the currency sign and {1} being the amount, but it does not take effect...

I got this from inside a TextMesh Pro in the Unity Editor, and I wonder if I can force changes on it.

<?xml version="1.0" encoding="utf-8"?>

<textarea fontName="0" materialName="1" size="0.7" baselineShift="0.12" kerning="custom" alignment="center" leading="0" verticalAlignment="center" contentWidth="shrink" width="3.11" height="1.11" xmlns="http://mycompany.com/unity/text/2013">
  <p>
    <span>$50</span>
  </p>
</textarea>