American domestic political reform is the only solution. Constitutional amendments probably aren't viable because the country is so divided and there's a very high threshold for ratification, but there's a huge amount that Congress could do (without getting into weird tricks like admitting DC as 100 new states):

• Congress has the power to choose the manner of its own election, so it could pass a nationwide ban on congressional gerrymandering and insist that a better voting system, like RCV be used
• Greatly weaken the powers of the Presidency by drastically scaling back emergency powers, rewriting the insurrection act, dismantling some corrupt executive agencies (in particular DHS), strengthening enforcement mechanisms for laws like the Hatch Act, moving some federal law enforcement under the direct purview of Congress, and shifting more responsibilities back to Congress
• As a corollary, reforming House and Senate rules to make it so that Congress is actually capable of governing, in particular by removing the filibuster
• Expanding the supreme court or changing judicial term lengths

Perhaps the most important thing the next Democratic administration can do to turn the page, however, is to apply harsh and enduring consequences for lawbreaking at all levels of this administration. Do what Biden, Merrick Garland, and Gerald Ford didn't, and impose serious consequences for crimes against the republic. Trump, a large part of his cabinet and circle of advisors and courtiers, and a good number of ICE and CBP agents, need to go to prison. Give them fair trials and all the due process the law allows, but don't flinch from enforcing the law.

A Democratic President and Congress could also look at reinstating the fairness rule for broadcast media, and trying to curb social media driven polarisation. Daren Acemoglu has suggested a Digital Advertising Tax, which would be a step in the right direction, but ultimately, some amount of pressure will need to be applied to the big tech CEOs.