Aside from the mandatory flattery required of Republican elected officials, there’s remarkably little testimony that Trump has involved himself in the process of governing. Tax reform was carried across the finish line by the GOP congressional leadership. Net neutrality was repealed by independent Republicans at the Federal Communications Commission.
Foreign policy is a more mixed bag. If the president deserves credit for the defeat of Islamic State, it’s because he let “the generals” do their thing. On the other hand, credit (or blame) for recognizing Jerusalem as the capital of Israel or pulling out of the Trans-Pacific Partnership and the Paris accord on climate change certainly goes to him.
In general, it seems to me that Trump’s success (such as it is) is less attributable to sudden mastery of the issues than to staying out of the way of rank-and-file Republican policymakers, activists, and bureaucrats.