I am trying to add line breaks (aka newlines) to values of the input
-element. 

,
,
and \n
aren't working; still everything is on one line.
I haven't found an answer to this question amongst other questions that solves my problem. Thanks in advance.
The input element does not support line breaks. Use the <textarea>
element as shown below:
<textarea id="multiliner" name="multiliner">line1
line2
line3</textarea>