Source -> Justify text will reflow one paragraph of text. Unfortuneatly you have to invoke it one paragraph at a time if you want the whole file reformatted.
I realize you may actually be looking for a viewing transformation that does not modify the file.
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inspectorG4dget
On
Yes this is possible. Here's how you would do this:
Edit > Preferences > Editor > Line Wrapping
In this window, make sure that the "Wrap Long Lines" box is checked. You can then edit settings in the same window like at what position the line show wrap, etc.
It seems like it's currently not possible.