Congress doesn’t need to expand the number of judges. FDR tried that and as popular as he was at the time, he failed. What they should do is urge the states to pass an amendment that limits judges to, say, ten years on the bench, or twelve. When the founders wrote the constitution, the average life expectancy was about 50 years. They had no way of knowing that 200 years later judges would be sitting on the bench well into their 80’s. of course, Democrats would fight that idea.
Of the first four Chief Justices, John Jay, Oliver Ellsworth, John Marshall, and Roger Taney, only Ellsworth died young (about 62). Just looking at their years of birth and death and not their actual birthdays, it appears Jay lived to 84, Marshall to 80, and Taney to 87.
(I'm ignoring John Rutledge, named as Jay's successor, whose nomination was rejected by the Senate.)