Biden was not all that mentally coherent, and you labor under the idea that Biden would have released these files if there was any damning information about Trump.
Biden never appeared to target his political enemies this way, in fact, Trump's problems arose from the accurate asessment of Russian (attempted) interference in our elections and his conspiracies surrounding this (and his inability to admit he lost), leading to a riot in the Capitol, but really it was being sued in state court, not federal court.
There is no precedence that would have shown Biden would have done anything with whats in the Epstein file, although this defense mechanism is what Trumpsters use to convince themselves he is innocent, even though he and Epstein were close friends. It would likely say in the file there is some connection between Melania and Epstein, as in she was groomed at one time by Epstein, or perhaps was in his network of contacts, and likely might have met Ghislane before she met Trump. That could be one reason Trump has buried the file.
I won't accuse him of solicitation of underage girls without some clarification on this happening. It could also be in the Epstein file, though.