By default, Excel will not allow circular references, which is why you receive warnings when it occurs on your workbook.
If you would like to turn it on, all you have to do is enable iterative calculations from the options.
To start, click on the ‘File’ tab.
Then, select ‘Options’ (the lowest options on the left-hand bar).
On the ‘Excel Options’ window, go to the ‘Formulas’ section and tick the ‘Enable iterative calculation’ box.
Click ‘OK’ to save the changes.
After that, you will not get any warning whenever there’s a circular reference.
However, we strongly advise you not to do this.