A lot of my foreign friends (and a disconcerting number of those in the United States) believe that the US election is over and that Biden won. They (at my guess, correctly) believe that Trump's lawsuits will fail -- but aren't familiar enough with the nitty-gritty details of the electoral college to realize that Trump still has a potential path to victory.
It is a very unfortunate fact that the Electoral College system relies on social norms and assumptions, not established codified law. And, of course, Trump loves to smash social norms and has been doing so his entire presidency. The scary reality is that there are no laws in the vast majority of states that prevent the state legislature from ignoring the vote in their state. They can legally send the electors that they choose who can then vote as they choose with no or minimal penalties. I wouldn't think that this is even a possibility -- except for the politics of the last five+ years.
The are a number of combinations of majority-Republican state legislatures that could reverse the election -- Pennsylvania, Georgia and Nevada are just the most obvious since their count lasted the longest. Michigan and Wisconsin also have majority-Republican legislatures with 16 electoral votes each. And this is a play that Trump and company are very aware of.
If you wish more details, read The Nation's The Election That Could Break America and/or Umair Haque's America Has a New President. Can It Keep Him?
Personally, I can't imagine California, the entirety of New England and a number of other states accepting this. The Republicans have already won two presidential contests (Bush vs. Gore and Trump vs. Clinton) in this century despite losing the majority of the vote. The Senate, where Republicans represent FAR fewer people than the Democrats, have had a majority that have made a mockery of both the impeachment and Supreme Court confirmation processes. There are substantial majorities of US citizens who support access to abortion, identical treatment for sexual minorities, less punishment for (if not outright legalization of) street drugs and a number of other issues who are ignored in favor of the opinions of a strident minority.
Legally, their only option is secession from the United States. I don't see a civil war happening because there is just no way in which the red states can beat the blue states (assuming that they even want to) and there will be enough people in the blue states who feel that they will be better off without the red states. The sad thing is . . . I really do wonder if this might not be the best thing for the United States . . . .