Not sure how "correct this is", but the argument I've read seems to think that the R state legislatures (and only the state legislatures) would be the only thing that matters.
The modus operandi went something like this according to a video I saw:
1) Base yourelf on this part of the US constitution
Each State shall appoint, in such Manner as the Legislature thereof may direct, a Number of Electors, equal to the whole Number of Senators and Representatives to which the State may be entitled in the Congress
2) Interpret that as literally only the state legislature
3) The R controlled state legislatures pass resolutions claiming that the election was rigged by Democrats and that no electors may be appointed (or alternatively, that Republican electors are appointed)
4) When this inevitably ends up in court, the conservative SC rules in favour of the state legislatures
5) Trump wins with a map comparable to the current statem legislature control map (without governors; which basically means WI/MI/PA/GA/AZ flipping to Trump); or the election goes to the House which then elects Trump
Do I think that is likely to happen? No, I am 99.9% sure it won't happen. But this is the method I think would be used if the election was to be stolen (which like I said I saw on some internet video so it is probably an inaccurate interpretation of the constitution and what not)
Doing this - handing Trump victory in an election which he has clearly lost - would invite secession and civil war. Even if that doomsday scenario didn't happen, you would have the not-so-small issue of other countries, including key allies like Canada and the UK, refusing to acknowledge Trump as the legitimate President. I don't see why the GOP would do this when their brand has held up pretty well, they'll almost certainly hold the Senate and be able to use it to block most of Biden's initiatives, and they have an excellent chance of winning in 2024 and having a trifecta at that point.
