There's plenty of precedent for changing the size of the Court via legislation. About the only way I could see SCOTUS making a ruling would be if a hypothetical Judiciary Reform Act affected the tenure of existing justices in some manner. For example, a bill that tried to shrink the Court immediately to 7 by removing the 2 junior most justices would get struck down unanimously.
The hardball play here would be to remove the two junior-most justices, “bow to public pressure” and expand the court back to nine, but add two new Biden justices rather than re-adding Kavanaugh and Barrett.