iirc, it was: economic nationalism + explicit white identitarianism.
and im gonna anticipate your response by saying these aren’t exactly characteristics unique to trump and have existed in the gop for decades.
It's a good question.
I think you can reframe it as a tactical question: do you still buy the logic of the Emerging Democratic Majority and the post-2012 GOP autopsy or do you think Trump's win in 2016 was a blueprint? That is, you've got a core of angry white guys who are shrinking as a percent of the population. Do you moderate on substance and/or tone to broaden your base, or do you rely on taking an even larger share of white guys while getting real aggressive on the procedural side of things (gerrymandering, disenfranchisement, NC/WI style shenanigans) to maintain power?
I think the last two Republican campaigns for governor in Virginia work decently as avatars for the two approaches. Ken Cuccinelli had a very right-wing record regarding gay rights, abortion, immigration, climate change, etc. but his campaign (in the wake of Romney's loss) clearly decided they needed to soften his image for the general election and mostly ran ads about how he'd fix traffic. In 2017, after Trump's win, they ran Ed Gillespie, consummate party insider: former high powered lobbyist, RNC chair, GWB advisor. In the primaries he beat out Corey Stewart who campaigned on preserving confederate heritage. In the general Gillespie, the establishment candidate, ran on a Trumpy platform of telling voters that MS-13 were going to invade their homes and kill their families.