Hmm…I found Shaun’s post helpful, but you need to extrapolate a bit 
.
If you inspect the HTML by clicking “Edit”, shown below, you will see how he adjusted the CSS color property of the icon.
Now all you need to do is adjust the function to target the font-size property instead, and pass along the desired icon size as an integer. The result is an icon with a different size than the text as shown here:
Let me know if I’m misunderstanding the request and I can try to help further. Good luck!