The thing is, it would set a precedent for all future presidents, it wouldn't be just about Trump and Biden. I don't know what Biden might do but it will be interesting to see how it all plays out.
Yeah but I think any and all political norms have been demolished in the United States.
Hyperpartisanship, dirty tricks, rank hypocrisy, a racist con-artist for president, and republicans in congress who enabled the worst of Trump's excesses are what the Republicans are all about. (And while the Democrats may not be perfect, their faults pale in comparison to the republicans.)
Whatever 'precedents' Biden might set, they will be ignored by the republicans if they think it gives them an political advantage. Remember, they are the party that were eager to impeach Clinton over a stained dress (technically a slightly different crime, but the thought is the same) yet thought it was wrong to impeach Trump over trying to blackmail a foreign country to interfere in the election.