To make all cells the same size in Excel, you can use the "Format Cells" option to adjust the column width and row height. Here are the steps to make all cells the same size in Excel:
Select all the cells in the worksheet by clicking the gray box at the top-left corner of the worksheet (above row 1 and to the left of column A).
Right-click on any of the selected cells and choose "Column Width" from the menu.
In the "Column Width" dialog box, enter a value for the width that you want all columns to be. For example, you could enter 10 to make all columns 10 characters wide.
Click "OK" to apply the column width to all selected cells.
Right-click on any of the selected cells again and choose "Row Height" from the menu.
In the "Row Height" dialog box, enter a value for the height that you want all rows to be. For example, you could enter 20 to make all rows 20 pixels tall.
Click "OK" to apply the row height to all selected cells.
Once you have completed these steps, all cells in the worksheet should be the same size. Keep in mind that this will adjust the size of all cells in the worksheet, so if you have cells that contain text or numbers that are wider or taller than the new cell size, you may need to adjust the column width or row height manually to accommodate the larger content.