It's still uncertain what Donald Trump's second presidency will look like, but his first administration was highly responsive to business issues with a set way of operating, top German business executive Joe Kaeser told CNBC.

"If I personally, for my company at the time, had an issue to resolve, his administration was extremely receptive," the chairman of the supervisory board of Siemens Energy said in an interview with CNBC's Annette Weisbach on Thursday. Kaeser was Siemens' CEO throughout President-elect Trump's first term.

Trump did "a lot of things which helped the economy" during his first four years in office, Kaeser said, noting that he believed the president-elect's tax cuts at the time were a positive.

Trump introduced a slew of tax changes, including lower federal income tax brackets and bigger standard deductions as well as changes to child tax credits, estate and gift tax exemptions and a deduction for pass-through businesses. One study done at the time, however, showed that the Trump tax cuts, which were implemented in 2017, only had a limited contribution to the strong U.S. growth the following year.

Taxes are again set to be top of the agenda for Trump as he takes office for the second time, alongside other economic policy plans, such as steep tariffs on imports and deregulation. Analysts have said that while it is tricky to determine how many of his proposals will be implemented, some of them could have global repercussions and impact countries and businesses.

Speaking to CNBC from New York, Kaeser said that Trump had "his way of doing things" but that he could "actually pretty much predict what happens and what doesn't happen, and so therefore that was actually a relatively easy way of understanding what needs to be done for the companies and the countries."

Despite the positive experiences with Trump's first administration, the former Siemens CEO said it was still unclear how the second term would play out.

A key difference now was that the Senate, House of Representatives, Supreme Court and White House were now all "looking in the same direction," Kaeser said. "I believe the jury's out on what that means."

"I think the conclusion we can take today for Germany and Europe, and by the way, also any other country, is that you better get prepared, because typically people like him [Trump], who have a very distinct style of leadership and reacting to, let's say different news, is that you can only deal with those people from a position of strength. If you are weak, you better not get in front of such an institution," he added.

Kaeser has in the past also been critical of Trump. In 2019, Trump verbally attacked four progressive Democratic congresswomen and in posts on social media, which prompted the crowd at a rally to chant "send her back" in reference to Rep. Ilhan Omar, D-Minn., who came to the U.S. as a refugee from Somalia as a child.

Responding to news reports about the event, Kaeser said at the time that it was weighing on him that the most important political position in the world was becoming the "face of racism and exclusion."

"I lived in the U.S. for many years and experienced freedom, tolerance and openness like never before. That was 'America Great at work,'" he said in a post on social media, according to a CNBC translation.