Unfortunately, there is no simple way to do that.
Your only functions you might count the number of letters and that doesn't give you a very good yard stick as iiiiiiiiii and WWWWWWWWWW are both the same number of characters.
There is a rather esoteric method that uses a script to "trim" the text to fit after the fact but it's rather complex to set up.
You can also go to layout mode, Position tab in the inspector. For tooltip type in Self. When you roll over the field, the full text will display.