Note: For the key binding, see the second part.
less, it's called line folding rather than line wrapping.
To set it not to fold, use the
Causes lines longer than the screen width to be chopped rather than folded. That is, the portion of a long line that does not fit in the screen width is not shown. The default is to fold long lines; that is, display the remainder on the next line.
Alternatively, as mentioned in the below comment, if you already opened the file, you can toggle the mode by typing
-S (and then Enter for some implementations).
After disabling line folding, you can scroll sideways with the arrow keys.