If there is no election result by January 20th, 2021, it is possible that Nancy Pelosi could be named acting President of the United States.
The Speaker of the House in 2021 would be the acting president if the electoral college doesn’t make a decision by January 20th, 2021
So, If the Democrats retain control of Congress and choose Pelosi to be Speaker she would technically be in line to serve as acting president.
According to Fox News:
“It might be right,” Napolitano told host Stuart Varney. “President Trump’s term ends at precisely noon on Jan. 20, 2021. If the Electoral College has not yet named a successor, presumably either Donald Trump or Joe Biden, then whoever is the speaker of the House would become the acting president of the United States.”