Hi Suresh,
We do have a Text Pad action that allows you to add specified character(s) to the begining, end, or both until the total text is of a specific lenght or a set number of times. The result will be populated to a variable. More information on this action can be found at the link below.
https://static.helpsystems.com/automate/help/ame_11/Default.htm#TechRef/Actions_Activities/Text/Text_-_Pad.htm%3FTocPath%3DTask%2520Builder%7CActions%252FActivities%7CText%7C_____9
