To insert linebreaks in a string you want to generate currently requires to open a quote on one line of the expression and close it on the next line (see https://forum.mendix.com/link/questions/90904 about how to insert them).
That does not exactly make expressions easy to read.
I would prefer just a function to be added to generate this and keep code readable.
Great suggestion Ilya and that works, only for ease of use and readabilty a function call with CRLF or Linebreak in the name would be easier to guess for newbies in Mendix
Have you tried urlDecode('%0A') ?