I'd say that's a very unrealistic expectation. RAs are not co-authors. In fact, if I received an application from a perspective PhD student who was listed as a co-author on a high quality publication, I would do a little digging to try and figure out what exact role the applicant had on the paper.
I most years, I would say zero percent of finance PhD applicants already have a top-3 publication. It's not even that common for job market candidates to have a top-3 publication at the time of graduation. So having one 5 years earlier is extremely rare.