Hi there, if you still need, I was able to adjust the font size of the statements and scale points in a MaxDiff Matrix question by using the below CSS. As both the statements and the 2 scale points are table header cells "th", the below CSS can be tweaked so that the font size of both get adjusted. Also, the "td" in the below will adjust the size of the radio buttons:
.Skin .Matrix table td, .Skin .Matrix table th {
  font-size: 24px;
}
To have the scale points and the statements be different sizes, this can be done by using more specific selectors. Without getting QIDs or JavaScript involved, CSS can be added to the HTML of the MaxDiff Question Text so that the styling only gets applied to that page in the survey. This is needed because the 2nd section in the below code could effect other questions if added to whole survey in the Custom CSS of the Look & Feel. The first bit adjusts the scale point text, the 2nd section the statement text, and the 3rd the radio buttons. Try adding the below to the Question Text using the Rich Content Editor's HTML/Source View "<>":

Click to write the question text