In Word, you have settings for line spacing, which apply to the space that is
added between lines when the document is viewed or printed. Excel, being a
spreadsheet program and not a word processor, doesn't have this setting. I
believe the closest you'll come is to set the alignment for the cell to Wrap
Text, and the vertical alignment to Justify. Then you can increase the row
height and get the appearance of "double spacing" within the cell. But if you
have some cells in the row that need, say, 5 lines, with others that need only
2, the latter cells will have much more space between lines than the former.