Days before Donald J. Trump became president in 2017, he promised to rein in his company’s freewheeling ways, assuring the American people that his family business would not “take advantage of” his presidency.

Nearly eight years later, he is making no such promises.

The former and possibly future president is cashing in on a variety of new ventures as he seeks a second term, without offering to reinstate the guardrails from his first, according to financial filings and interviews with people familiar with his finances.

The ethics plan Mr. Trump imposed on himself when he was in the White House had limitations and its share of critics, but would prohibit much of this current deal-making.

Even if Mr. Trump eventually agrees to forgo future foreign business — the centerpiece of that earlier plan — the recent deals will most likely be grandfathered in, because his company moved swiftly to announce them well ahead of any potential new constraints, one of the people said.

This year alone, the Trump Organization struck real estate deals in Vietnam, Saudi Arabia and the United Arab Emirates, countries that are central to American foreign policy interests.