I took a glance at all the presidential election data and found a few presidents-elect who lost their home state, depending on you define it. There was Trump, as you mentioned, but also the arguable cases of George H.W. Bush, Richard Nixon, Woodrow Wilson, and James K. Polk.

In the 1988 election, Bush lost Massachusetts (where he was born and where attended prep school) by 7.85 points, and lost Connecticut (where he was raised and where he attended college) by 12.13 points.

In the 1968 election, Nixon lost New York (where he lived and practiced law from 1962 until the election) by 5.46 points.

In the 1916 election, Woodrow Wilson lost New Jersey (where he was the incumbent governor) by 11.72 points. His case is the most interesting to me, because he's the one of two people I mentioned that actually ran for and won an election in his home state, and yet he lost his home state by a large margin.

In the 1844 election, James K. Polk lost Tennessee (where he was the incumbent governor) by 1.00 point.

Unlike the other presidents-elect I mentioned, Trump's home state is unambiguous. He is from New York, which he lost by 21.05 points. And he only got 10% of the vote in New York County, where his penthouse and Trump Tower are. But he never ran for election in his home state.

So, as far as I can tell, Trump lost his home state by a larger margin than any other president-elect. But of course, the answer depends on how you define "home state."

(Election data gathered from uselectionatlas.org)