C7 of the Penn Common Data Set lists interviews as “important.” However, not everyone will get an interview so I think it’s just another data point for them to consider. You’ll notice the CDS lists standardized test scores as “very important,” but Penn is test-optional this cycle. So, if one submits a score—great!—another data point, but they won’t hold it against applicants who don’t submit scores. I think it’s the same for interviews.
There was a lot of discussion about interviews in last year’s admission thread too. You can search through it to see how applicants fared (interview vs non-interview).