In May of 2020, Biden committed not to pardon Trump or otherwise interfere with any investigations that the Justice Department may or may not carry out:
Democratic candidate Joe Biden said that if he wins the presidency he would not use his power to pardon Donald Trump or stop any investigations of Trump and his associates.
“It is not something the president is entitled to do, to direct a prosecution or decide to drop a case,” Biden said Thursday on MSNBC. “It’s a dereliction of duty.”
The former vice president made his statement in response to a voter who asked him on Lawrence O’Donnell’s show, “The Last Word,” whether he would “commit to not pulling a Gerald Ford in giving Donald Trump a pardon under the pretense of healing the nation.”
Biden responded, “I commit,” before offering a more lengthy explanation of his view that the president must allow the Justice Department to operate without interference.
Biden says he would not pardon Trump or block investigations - AP, May 15, 2020
Recently, though, Biden has expressed more hesitancy about aggressive Federal investigations of Trump. NBC reports that he has told his advisors that he worries that such investigations would be overly divisive and keep the focus on Trump, rather than his own Presidency:
President-elect Joe Biden has privately told advisers that he doesn't want his presidency to be consumed by investigations of his predecessor, according to five people familiar with the discussions, despite pressure from some Democrats who want inquiries into President Donald Trump, his policies and members of his administration.
Biden has raised concerns that investigations would further divide a country he is trying to unite and risk making every day of his presidency about Trump, said the sources, who spoke on background to offer details of private conversations.
Still, least for now, this desire seems to be taking the form of a hands-off approach to the actions of the Justice department:
As Biden tries to balance his own inclinations with pressures from within his party, his advisers stressed that he is seeking to reset the dynamic between the White House and the Justice Department from what it has been under Trump.
Biden wants his Justice Department to function independently from the White House, aides said, and Biden isn't going to tell federal law enforcement officials whom or what to investigate or not to investigate.
"His overarching view is that we need to move the country forward," an adviser said. "But the most important thing on this is that he will not interfere with his Justice Department and not politicize his Justice Department."
"He can set a tone about what he thinks should be done," a Biden adviser said. But, the adviser said, "he's not going to be a president who directs the Justice Department one way or the other."
Biden hopes to avoid divisive Trump investigations, preferring unity - NBC News, Nov 17, 2020
This does not contradict his previous statements, and a pardon would be politically impossible, and wouldn't protect Trump from ongoing State investigations anyway, but it's certainly possible that Biden would prefer to see any investigations of Trump happen at the State level.