The full plan is detailed here: https://www.thenation.com/article/politics/little-secret-trump-johnson-election/.
Basically, they just need enough States to withhold submitting valid slates of electors, which are due on Dec 11th. If that doesn’t happen, and it lowers the amount of electoral college voters enough so no single candidate has a majority, then the US House gets to decide.
In other words, we’re fully reliant on GOP controlled States doing the right thing. We’re fucked.
https://pmc.ncbi.nlm.nih.gov/articles/PMC9542152/