Film/ animation interactions with objects and eachother

Hi! Im new to unreal engine amd animation entirely but really wamting to learn.

To get your character to, for example pick up a ball and bounce it off a wall, do you program him to that before recording like a game(and hes actually grabbing it)? Or do you have to animate the ball separately and line it up with the character to just make it “seem” like hes picking up the ball?

Also, if 2 characters high five, are they really high fiving? Or are they independently recorded and just lined up perfectly to fake a high five?

Hope i asked that well enough.
Thanks!