I was working on a matrix Visual and needed to add a simple linebreak to the text in the values section. To do this is actually really easy.
bookingstitle = CONCATENATE(timewax_planning_bookings[resources.bookings.projectName],
CONCATENATE(UNICHAR(10) &" ",
CONCATENATE(timewax_planning_bookings[resources.bookings.from],
CONCATENATE("-",CONCATENATE(timewax_planning_bookings[resources.bookings.to],"")))))
You can use the UNICHAR(10) code to add a linebreak into your text.