WASHINGTON — On his first full day back in the White House, President Donald Trump reveled in his return to power and vowed to do what no president had ever done before. “We’re going to do things that people will be shocked at,” he declared.

Of all the thousands of words that Trump uttered during his fact-challenged, talkathon-style opening days as the nation’s 47th president, those may have been the truest. No matter that much of what he was doing he had promised on the campaign trail. He succeeded in shocking nonetheless.

Not so much by the ferocity of the policy shifts or ideological swings that invariably come with a party change in the White House, but through norm-shattering, democracy-testing assertions of personal power that defy the courts, Congress and the ethical lines that constrained past presidents.

He freed even the most violent of the rioters who assaulted the Capitol in his name four years ago. Out of pique over questions of loyalty, he stripped former advisers facing credible death threats of their security details. Disregarding a law passed with bipartisan support and upheld by the Supreme Court, he allowed the Chinese-owned TikTok app to remain in use in the United States despite serious national security concerns.

Not satisfied to simply eliminate diversity, equity and inclusion initiatives, he ordered government workers to snitch on anyone suspected of not going along or face “adverse consequences,” a practice familiar to anyone of a certain age who lived in Russia. He fired at least a dozen inspectors general who monitor departments for corruption and abuse in a late-night purge Friday, ignoring a law requiring him to give Congress 30 days’ notice and provide specific reasons.

In doing so, Trump in effect declared that he was willing and even eager to push the boundaries of his authority, the resilience of American institutions, the strength of the nearly 2 1/2-century-old system and the tolerance of some of his own allies. Even more than in his first term, he has mounted a fundamental challenge to expectations of what a president can and should do, demonstrating a belief that the rules his predecessors largely followed are meant to be bent, bypassed or broken.

“He’s using the tools of government to challenge the limits on the post-Watergate presidency,” said Brendan Nyhan, a government professor at Dartmouth College. “Some of these efforts will be turned back by the courts, but the level of anticipatory obedience we’re seeing from business, universities and the media is unlike anything I’ve seen in my lifetime.”

Not everything that shocked people in Trump’s first week necessarily violated presidential standards. Any time a president from one party takes over from one of the other, the shifts in policies can be head-snapping, and Trump has been particularly aggressive in reversing the country’s direction ideologically and politically.

It is broadly within a president’s power, for instance, to change the government’s approach to diversity programs, to pull out of an international climate agreement or to fire holdover political appointees. But as so often happens with Trump, he takes even those decisions one step further.

“The theme of this week was vengeance and retribution when all other presidents have used their inaugurations to heal wounds, bring people together and focus on the future,” said Lindsay M. Chervinsky, executive director of the George Washington Presidential Library and author of several books on the presidency. “That sounds like a norm, but it’s actually fundamental to the survival of the republic.”

Trump has never been too impressed with the argument that he should or should not do something because that is the way it has been done. As a government novice in his first term, he found himself flummoxed at times by how Washington worked and unable to exert his will to achieve major priorities.

He returns for this second term more prepared and more determined to crash through obstacles and any supposed “deep state” in his way. Ideas that establishment advisers talked him out of the last time, he is pursuing this time with a new cast of more like-minded aides.

He decided to rewrite the 14th Amendment to the Constitution as it has been understood for over a century to declare it does not guarantee automatic citizenship to all children born in the United States. It took just three days for a federal judge to temporarily block the move, but the issue will surely go to the Supreme Court.

While other presidents put their assets in a blind trust or otherwise distanced themselves from their personal business interests upon taking office to avoid even the whiff of a conflict of interest, Trump exploited his political celebrity to make enormous amounts of money in a scheme that could potentially be fueled by investors with a stake in federal government policies.

Just three days before his inauguration, he released a crypto token called $Trump that together with other family tokens rose to around $10 billion in value on paper. The tokens create new opportunities for companies and other financial players inside and outside the United States to curry favor with the new administration.

Moreover, while other presidents had wealthy patrons who enjoyed access to the Oval Office, Trump has gone so far as to surround himself with billionaires on the inaugural platform and actually give an office in the White House complex to Elon Musk, the world’s richest man, with a mandate to revamp the federal government that puts billions of dollars in his pocket through various contracts.