I’d lower the barrier for presidential impeachment and removal from office. 67% is too high. It can be lowered to 60%. And yes, I know this could be used against a Democratic president, but I don’t foresee Republicans ever getting to a large enough Congressional majority to pull it off. 60% is at the threshold where it can only be used to depose Trump-like presidents but none others.
Secondly, repeal of Electoral College, and also amend the 26th Amendment to make it far easier for a Cabinet to rule a president as being unfit for office.
Thirdly, abolish all filibusters. Legislation must move swiftly to a yes/no vote each time.
Fourthly, all presidential-issued pardons must pass Congress by a majority vote in order to be valid.
Fifthly, cap all presidential/Congressional/gubernatorial candidates at age 65 to run for office, and put in term limits for Congress.
Sixthly, crackdown heavily on social-media speech that is factually wrong. Debate about things that are subjective (my sports team vs yours, which movie is better, pineapple on pizza being delicious or disgusting,) is totally fine, but any sort of factually wrong statements like the Moon landing being faked or Earth being flat will lead to stiff penalties.
Seventhly, much tougher crackdown on the media. This would require repeal or revision of the First Amendment. Congress has to pass laws that severely crack down on misinformation.
Eight, all gerrymandering is banned.
Ninthly, all presidential candidates would be required to possess a minimum of 10 years in public service, military service, elected office or some similar position, and pass a rigorous political-economic-history-etc. test (think something like SATs, but tougher.)
Tenthly, all voters must be capable of passing the equivalent of a US citizenship test/exam of knowledge. After all, if only US citizens can vote, and foreigners have to pass the test to become a US citizen, then it’s only fair that US citizens born in America itself should have to pass the same test that foreigners-turned-naturalized-Americans have to pass.