IMO the politics of the language around this stuff matters a lot more than the academic definitions right now. That said, I do think Trump and the GOP's ongoing actions constitute an attempted consolidation of incumbent advantage, a.k.a. autogolpe. Outcome TBD. https://twitter.com/GregWeeksCLT/status/1326136712314167296
Since the early 1990s, consolidation of incumbent advantage has been the dominant mode of democratic breakdown worldwide, so there are plenty of relevant examples. Coups involving the direct use or threat of force have become comparatively rare.
A consolidation of incumbent advantage occurs when the incumbent party uses its power to effectively ensure that it stays in power, even as "competitive" elections continue. They usually involve tilting the electoral playing field, but they can involve "judicial coups" as well.
This is exactly the scenario that most worried many of us going into this election. Polls showed Biden/Harris with a strong lead, but Trump was telegraphing his intent to pursue this exact strategy.
I think it will *probably* fail, and I certainly hope it will, but I am taking nothing for granted. I also suspect that the groups organized ahead of the election to protect the results will recognize this for the serious threat it is and will continue to turn up to oppose it.