So your example of Trump forcing the senate to do something they were against while president is an article about something that happened a year after he was president? I'm not even sure what the relevant part of that article is.
The entire point of whipping is influence and coercion and not literal power enunciated in a charter, bylaw, constitution, or parliamentary procedure you seem to be looking for.
Like McConnell, Republican Sen. Lindsey Graham, a friend and ally of the former president, was clear in his denunciation of Trump immediately following the Jan. 6 attack.
“All I can say is count me out. Enough is enough,” he’d said then.
On Thursday, however, Graham, who remains close to Trump, marked the occasion with a mix of shock and partisan attacks.
The author does on to describe the "GOP’s transformation into the Party of Trump" but Trump didn't do any of this by some manipulation of enumerated power as taught in high school civics about the separation of powers. He did it by appealing to voters and forcing Senators to follow him.
Biden can't appeal to Democrats on things the public already favors because he is a poor leader.