The text area in a form is sized by columns and rows in the default font used for input items. This property reflects the COLS HTML tag attribute in the <TEXTAREA> HTML tag that instantiates this object.
Style sheets are about the only way you can control the appearance of these cells because it is the only way the default input font can be changed. If the font size changes then the size of the TEXTAREA extent rectangle must change too. This might affect the layout of the page.