Biden's job IMO, is to prepare the Democratic party and the country for a shift to the left.
That's going to start with things like legalising weed, decreasing the prison population, keeping or expanding medicare 4 all etc but the big one is pushing through a new voters rights act that stops voter suppression in states like Florida, Texas, South Carolina.
Trump was right when he said this last year about the voters rights bill - "They had things, levels of voting that if you’d ever agreed to it, you’d never have a Republican elected in this country again.”
That's how Biden can shift the whole country, not just the Democrats left.
The republican party only wins in a country where the vote is suppressed and where gerrymandering is rampant. If Biden and a Democratic congress can bring US elections into the 20th century, the Republicans will have no choice but to move back to the centre.