While there are now many versions of realism (Classic, Structural, Offensive, Defensive, Neo-Classical, Constructivist and soon Neo-Neo), there are some core aspects and "seeing the world as it is, not as we would like it to be" is about as core as it gets. So, too, is focusing less on institutions and law and norms and what is right, but what is best for a country, putting it "first." That Trump occasionally says that the US should get out of various wars plays well in the Realist Restraint crowd..@VP Mike Pence spoke at #MSC2019 today to lay out the U.S. administration's view on international affairs and the U.S. role in the world. pic.twitter.com/Wy7xHqBk8A— Security Conference (@MunSecConf) February 16, 2019
However, the fundamental shared component of most, if not all, flavors of realism is that countries pursue either security or power, and that a Realist foreign policy would focus on maximizing one or or the other in a rational way. That means gathering as much info as one can about the capabilities of the adversaries (and allies), trying to assess which options will lead to which outcomes, and picking the ones that are most likely to do the least harm to one's own standing and perhaps pick those that are most likely to improve one's standing.
Is Trump Kennan or Kissinger? That is, focusing on how best to maximize American security or power? Just focusing on the intel end should be instructive---that Trump blows secrets when he pays attention and he mostly does not pay attention to the intel. How can you maximize security or power if you don't pay attention to the capabilities of the adversaries and the allies?
Realists tend to disagree about the value of allies, although they are generally seen as more valuable in a multipolar world. Antagonizing allies by levying tariffs on them is not something most realists would recommend.
Realists would generally argue that allowing one's country to be penetrated by the intelligence efforts of an adversary to be a bad thing. While realists vary in how important they consider domestic politics, I am pretty sure most would find interference in one's own elections to be problematic and that they would recommend both penalizing the perpetrator and improving one's defenses. What does Trump do? Cut the folks doing the defending.
Realists would never give up a bargaining chip without getting something for it--again, maximizing power or security tends to mean not giving things away. Agreeing to move the US embassy to Jerusalem without getting anything from Israel is the example in my head at the moment, but I am sure we can think of others. Oh wait, how about meeting with the leader of North Korea, a key concession that they wanted and getting nothing for it?
Containing adversaries is a favorite Realist tactic, so the Trans Pacific Partnership, aimed at containing China, would seem to be a good thing, but was one of the first things Trump rejected.
The whole North Korean situation should drive Realists mad. That the US bargains hard with South Korea over the costs of basing troops at a time where the US is negotiating over North Korea's weapons programs would seem strange to any Realist, right? Unless the cost of basing is more important than NK's nuclear weapons programs?
I could go on and on. The key thing is this: has Trump acted to protect American security and/or maximize American power? Mostly not. He has frittered away key elements of American power, mostly for his own personal interests, partly due to his embraced ignorance. Would Pence have a more Realist foreign policy? Maybe, hard to be less Realist than Trump's.