FDR notoriously promised a balanced budget during the 1932 campaign. Once in office, he became a Keynesian due to the absence of any other viable alternatives in the face of an emergency. The country effectively shifted to the left, and has never been the same again.
In 2020, Biden ran as the moderate candidate in the primaries–not the promoter of massive structural changes. Could that change as the result of the virus?
Yes. Once again, circumstances could require it. Time will tell.