Select the cells, rows, or columns you want to resize
To make cells wider, drag the right border of the column header
To make cells taller, drag the bottom border of the row header
Double-click the border of a column header to auto-fit the column width
Double-click the border of a row header to auto-fit the row height
Select multiple columns or rows before dragging to resize them together
Use Home > Format > Column Width to enter a specific width
Use Home > Format > Row Height to enter a specific height
Use Home > Format > AutoFit Column Width to fit contents automatically
Use Home > Format > AutoFit Row Height to fit contents automatically
Increase the zoom level if you want cells to appear bigger on screen
Merge adjacent cells if you want a larger single cell area