Select the rows or columns you want to resize
Right-click the selected row or column headers
Click Row Height or Column Width
Enter the same value for each selected row or column
Click OK
To make cells both the same height and width, adjust both row height and column width
To make multiple cells match one cell, copy the size by using Format Painter or manually set the same row height and column width
To auto-fit cells evenly, select the range and use Home > Format > AutoFit Row Height or AutoFit Column Width