I am unable to upgrade my relatively new (1 yr old) iMac to Big Sur. The program says I have insufficient space. When I look at the Storage section of my System Information, it says there is 260 GB being allocated to Other .

I am unable to upgrade my relatively new (1 yr old) iMac to Big Sur. The program says I have insufficient space. When I look at the Storage section of my System Information, it says there is 260 GB being allocated to Other . Not apps, system, photos, documents. I do not know what Other is. This is not occurring on my older computer that this one replaces. How can I find out what Other is that is using up so much storage?