Since Excel is a grid...you can't actually change the size of a single cell.
However, that doesn't mean you can't get the effect you're looking for by merging cells.
Example:
• Select cells B2:B4
• CTRL+1...to open the formatting window
• Click the Alignment tab
• Check: Merge cells
The selected cells will be "combined" into what appears to be one cell.
Note: Merged cells can be problematic in some sorting and selecting operations. But, used sparingly, they can be effective.
Does that help?