You can copy sketches and bodies by selecting the Copy badge: . This badge appears when you make a selection to transform with the Move/Rotate, Scale, Rotate around axis, and Mirror functions.
Once you turn on the copy function, the badge changes to when selected. To turn off copying, just select the badge again.
Note that you won’t see the badges when you use the Translate tool. Instead, you’ll see the Copy switch.
You can also copy a group of sketches, bodies, and reference geometries from the Items manager. Select the items you want to copy, and then the Copy badge. You can then reposition the copy by dragging the copied items. As soon as you exit the copy mode, you'll notice that the copies are added to the Items manager as new items.