The charts above are from the Gallup Poll. The survey was done between November 5th and 19th of a national sample of 1,018 adults, with a 4 point margin of error.
It shows that Joe Biden's favorability rating has risen by 6 points since the election. Donald Trump's has dropped by 3 points. Note that since 2000, no candidate's rating has dropped (whether they won or lost) except Trump. That's likely because of the way he's been such a sore loser.