Even though this is a serious necro I guess it's time to answer it.
You can accomplish this with CSS. Unfortunately, the text element does not allow you to directly input CSS and change it so you'll have to get really creative with CSS files, something that would take a while to explain.
Suffice it to say, it CAN be done.
Here's an image of a text element with 144pt font and an HTMLELement plugin with the font size set to 100vw (percentage of viewport width)
The text in the HTMLElement looks like this:
<div style = "font-size:100vw;">
Text
</div>
Now, why the text element doesn't allow > 144pt, I dunno. Why it doesn't allow you to set CSS properties like the text input does? I dunno.