The Text component's Shrink Font to Fit Minimum Size property is used to adjust the minimum size of the font to shrink the text. You can see this property in the Properties Panel.

The image below shows this property in action.

Shrink font to fit minimum size property set to 1, font Arial, size 8pt

Shrink font to fit minimum size property set to 4, font Arial, size 8pt

caution: Works in conjunction with the Shrink Font To Fit property set to true.