The text running into the icon after it wraps is a side-effect of disabling the trunctation… part of the reason it’s hidden away as an advanced option. 
The recommended approach is typically to customize the labels on the tiles to better fit the needs of the dashboard.
For example, if my device was named “Living Room Temperature Sensor” and I was building a dashboard showing the status of all my temperature sensors, I might rename the tile to just “Living Room”.
That’s a fair point on adding an option for changing the font size. We’ve got it on the hitlist, so I’ve noted your feedback!
You can change the size of the font used for the content in the Hero Attribute tile using the ‘Main Content Size’ option:
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Can you share a screenshot of your dashboard? It might help with coming up with other suggestions. 
Edit: Just an update that the Themes and Styles feature was released which provides control over the size of header font size.