Better Text can resize the Font Size according to the current resolution / dpi with the Font Sizer.
It also provides three kinds of Fitting Modes:
Will just affect the font size of the text using the Font Sizer. If the size becomes too large, parts of the text may be cut off or overflow the bounds (depending on the overflow settings).
Stay in Bounds (default)
The size is affected by the Font Sizer. But if the text wouldn't fit inside its bounds anymore the size is reduced to fit in.
Equal to the "Best Fit" option of uGUI. The text will grow or shrink to fit inside the bounds. The Min Size and Max Size values of the Font Sizer are used to avoid too small or too large font sizes.