更改pdftk可填写字段中的字体样式

Question

I am using pdftk for filling the value in pdf forms.

Req:

Need to change font size and style based on string length in programmatically.

Is there any way to change the font style for all textboxes programmatically?

$pdf = new Pdf($localFilePath);
$dataFields=$result[$name]['datafield'];
$pdf->fillForm($dataFields)->flatten()->saveAs($localFilePath);

Please suggest any idea to fix this