Can we reduce the size of an Excel file ?

Yes. We can use an online compressor to reduce the fie size.

Yess,we can reduce the size of an excel file.

If you Don’t want to edit or make changes to your Excel File, but still want to reduce the file size? Then the best option will be Zip’ing the excel file, it will reduce upto 90% of file size depending upon the images and objects in the excel file

Shrink the excel file size more than 50% without losing DATA

please see the below link 

https://www.youtube.com/watch?v=6Oy63vU1nD0

Save the file to Excel in binary (.xlsb). Doing this structures the workbook into a compressed folder that has many binary files. The amount of compression that you're going to get depends on the contents of the workbook. Also, you may find that opening, closing and saving the file takes longer than something saved just in regular (.xls) format.[1]

• After you've saved the file as an .xlsb, highlight and delete all of the cells outside the data range (typically to the right and below).
• Highlight the same cells and delete all formatting (colors, lines, etc.). Delete formatting for each for each sheet within the workbook.
• Re-save the workbook as an .xlsx file. Check to see how much these actions reduced the file size.

We need fist to define the file size.

is it the bytes of the file? is is the number of rows and columns? is it the calculation time for each sheet. etc..

there are plenty ways to reduce the file size of you mean just the bytes of the file.

1. remove extra unnecessary formatting
2.  avoid selecting the entire row and column and give it a format.
3. remove extra rows and columns that are blanks. use Ctrl+End to know where is the last cell.
4. there is more advance techniques in case this is not enough.

thank you for the question