Biden and Harris (and establishment democrats in general) are amenable to public pressure. The democrats are a party publicly committed to equality so they have to take a variety of opinions into account, regardless of the leaders’ own views. Trump does not; he’s only beholden to mega rich private donors, his strategists and other autocrats around the world. Like other corrupt people who many want to hold to account, has a lot to lose by not winning, and will be working to keep in power indefinitely it has recently been revealed.
A lot of the current chaos in the Near and Middle East right now is directly correlated to actions by him as president, and he did it strategically (like how leaving Afghanistan without process brought the taliban fanatics back into power, very convenient for someone who needs muslims to look bad). He has long been empowering racism and religious fanaticism, of people who really believe in the end of days, and is using the ideology of Traditionalism to grow that voter base mixed in with mythology of himself as savior. He has many of these strategies in common with other corrupt regimes like those of Putin, Netanyahu and Maduro.