You cannot force the caption of a Pro Button to wrap. However, your add-in button's caption will wrap using the same rules as a Pro Button. So for example, if your button caption is "Select by Attributes" you will see the same wrapping behavior as the Pro's Select by Attributes button.
Also, note - The caption for a button can only take up 2 lines on the ribbon. So if you have a really long button caption, it will take up that amount of space on the ribbon.
Thank you for the quick update... Really appreciate... It would be great if you could let me know the Process for wrapping up my custom button caption... What and where do I need to change the settings to wrap up my custom button.
Please open the config.daml file of you add-in project and find you custom button, then change the text in the caption attribute from "DataPreparation" to "Data Preparation" or "Prepare Data" (please note the space between words). Then rebuild and run the add-in.