Different Font Sizes Within PARAGRAPHTEXT

Is it possible to assign via javascript different font sizes to each line I add via the function below??

For example if I enter as the content "Title\nSubtitle" so have it appear something like this all with in the same text item?

TITLE

SUBTITLE

function createText(artLayerRef, fface, size, colR, colG, colB, content, tX, tY)

{

  artLayerRef.kind = LayerKind.TEXT

  textColor = new SolidColor();

  textColor.rgb.red = colR;

  textColor.rgb.green = colG;

  textColor.rgb.blue = colB;

  //Get a reference to the text item so that we can add the text and format it a bit

  textItemRef = artLayerRef.textItem;

  textItemRef.kind = TextType.PARAGRAPHTEXT; 

  textItemRef.contents = content;

  textItemRef.font = fface;

  textItemRef.color = textColor;

  textItemRef.leading = size/(600/72);

  textItemRef.width = 110;  

  textItemRef.height = size/2;  

  textItemRef.justification=Justification.CENTER;

  textItemRef.size = size/(600/72);

  //textItemRef.position = new Array(tX, tY) //pixels from the left, pixels from the top

  textItemRef.position = new Array(tX-textItemRef.width*(600/72)/2, tY ) //pixels from the left, pixels from the top

  textItemRef.hyphenation = false;

}