In the text area you would write your answer as normal, however to make the second line appear with differently styling you can wrap the 2nd line with *.
An example of a submit button would look like this:
Submit button*take me to the next question*
This also works for most answer widgets. you can try it on button lists, checkbox lists, choice buttons, dropdowns and radio button lists.
This is the first line of your answer*This is the second line of your answer*.