Pressing the CommandCtrl+Enter keys inserts a manual line break. This shortcut works directly in the cell or in the input line. The input line can be expanded to the multi-line by the Down arrow button on the right.
If you want the text to automatically break at the right border of the cell, proceed as follows:
Select all the cells where you want the text to break at the right border.
In Wrap text automatically option and click OK., mark the
For automatic wrapping in XLS files, the rows in question should be set to Optimal Height.