If you want to use Debroop suggestion, it would be to create a new attribute on Project of type 'calculated' with expression 'DateDiff(baseline_finish,schedule_finish,"Day")'
But this may not meet your requirement as 1) it needs a baseline to be set 2) it doesn't take into account todays date (eg if you have a project which has baseline_finish and schedule_finish being 2 months ago and is still active, the date difference will be 0).
You can also look at the query 'Program Manager Schedule Dashboard' which uses a database view cop_inv_days_late_v. 'Project Manager Schedule Dashboard' also has 'days late'.
Personally, I would be looking at how your oganisation wants to use "Days Late" and if it should be based on baseline as well as 'today' and to see if the above could be used.
As an example, on Task there is an attibute 'Is Late'. If the task doesn't have a baseline to compare against, the 'Is Late' is green, even if the task was scheduled be completed 5 years ago, and is still not completed and doesn't have a baseline.