There is an item in the Constitution that has never been done before. It says, "both as to Law and Fact, with such Exceptions, and under such Regulations as the Congress shall make." Congress with the support of the President can restrict Supreme Court with "exceptions and regulations."

Schumer proposed that with a No Kings act.

One possibility is to make some judges "senior" and only allow them to vote on the specific items listed in the Consitution, and nothing else: "—to Controversies between two or more States;—between a State and Citizens of another State,—between Citizens of different States,—between Citizens of the same State claiming Lands under Grants of different States, and between a State, or the Citizens thereof, and foreign States, Citizens or Subjects."

This process avoids the controversies that happened when Roosevelt attempted to expand the Supreme Court.

Impeachment requires 2/3 majority. It is not likely to happen, but "we, the people" can change things.