The real check here is for congress to write laws that are actually specific in their text. That is hard, though, so they instead write laws that empower parts of the executive branch to do some broadly-defined thing, including the power to make the relevant rules. When you get an executive who doesn't play your game, those poorly-written laws come back to bite you.
No, the real check is impeachment of executive officers when they flagrantly violate the law.
The tradgedy of Trump's first term was that the House of Representatives undermined the legitimacy of that check by using it in partisan, ambiguous and non-compelling circumstances, and failing as a result to obtain a conviction. Using the heavy machinery of impeachment ineffectively made it harder to use should the executive take the tremendous steps you're suggesting.
Anyway, Trump just mocked the leader of a foreign ally for refusing to hold elections. Viewed together, his comments sound like an extended troll of the political opposition.
That's an overly simplistic view of governance.
You're effectively says Congress should mandate every detail of every regulation. Even in areas where knowledge is changing (level of chemicals that are toxic, which medicines are useful and safe, etc).
The whole premise of our system is that the people within the system operate in good faith. And that's worked for most of 200+ years. I would posit that no amount of legislation will be able to stop bad-faith actors from screwing up the system, even more so when they convince ~50% of the voting popular that "burn it to the ground" is a reasonable take.