To do this, America will need to curb the power of its president. That means doing such things as...
1. Disallowing (in Law) the "nuclear option" for important appointments so that presidents can't stack departments with partisans. This would mean that Judges, the Attorney General and other important appointments must pass a very high bar, a super majority (67-33) or even more, say 80-20 before they can be approved. It would mean that even a corrupt president like Trump could not force through corrupt people like Barr as AG, and totally unsuitable people like Drunky to the bench
2. Taking away the absolute power of the pardon. Make pardons have to be only recommended by the president, and ratified by the Senate by a 2/3 majority. This would prevent a future Trump (i.e. a corrupt president) from dangling pardons to obstruct justice.
3. Taking away the President's power to fire cabinet members without Senate approval, and his ability to appoint acting temporaries to get around the Senate approval step. e.g., if the AG is fired or resigns, the deputy AG automatically becomes the Acting AG by default.
4. Taking away the president's power to declare a National Emergency. Put that in the purview of Congress.