We need to pass an amendment that fixes the number of Supreme Court Justices at 9.
Packing the court is the easiest way to overthrow the Constitution (since, after that, anything you do is “Constitutional”), and the Constitution currently doesn’t specify the number of Justices, which means a simple majority in Congress can change it!
To prevent this, an amendment must be passed. If anyone’s serious about preserving democracy, this should be priority number one!