\linebreak[number]
The \linebreak command tells LaTeX to break the current line at
the point of the command. With the optional argument, number,
you can convert the \linebreak command from a demand to a
request. The number must be a number from 0 to 4. The higher the
number, the more insistent the request is.
The \linebreak command causes LaTeX to stretch the line so it
extends to the right margin.