An image circulated online via social media purports to show former vice president and 2020 Democratic presidential nominee Joe Biden kissing a young girl on the cheek, typically accompanied by comments labeling the picture as "sick," "disgusting," and inappropriate:
Whatever one might think of the propriety of the pictured activity, it has nothing to do with any U.S. politician. It's actually an image of Mexican president Andrés Manuel López Obrador, taken from a March 2020 video showing him greeting enthusiasts outside a hotel in Ometepec in south-western Mexico:
Here's another screenshot from the video, showing more clearly that the person in question is Obrador and not Biden: