Trump's path to "victory" lies in inciting his most rabid brownshirts to coup for him (again), not expanding his appeal to actually win more EC votes than Harris.
How would he pull this off though with Biden as president? They didn’t even make it with all their efforts when the white house was on their side, but now it’s not. I believe he would if he could, but I don’t think it’s a viable option this time around.
TL;DR: because this time they have state election officials on their side.
They will create enough FUD about the results to either get Trump EC votes he didn't legitimately win, or to throw out enough EC votes entirely that neither candidate gets to 270 and the election is decided by a "one state, one vote" poll in the House.
Last time, the 50+ lawsuits trying to throw out election results failed because there was no fraud to be found. This time, they will succeed because disposable MAGA followers will have manufactured it themselves. As we've seen with those previous lawsuits as well as Trump v United States, the MAGA SCOTUS won't go so far as to blatantly ignore 100% of reality to rule in favor of Trump, but will seize upon any flimsy excuse they can find to spin their decisions in his favor. Any real election fraud -- even if we all know it's done on Trump's behalf -- will be the fig leaf that covers SCOTUS as it falls over itself to coronate him.
So the coup you’re talking about here is a non-violent one or do you think the election interference claims will rial enough anger with the system to make people get up en mass and fight?