Copy Bone
Copies a bone transform to another bone
UAnimGraphNode_CopyBone
FAnimNode_CopyBone
Copies the transform completely or partially of one bone, the Source Bone, to a another bone, the Target Bone.
There are options to copy any combination of rotation, translation, and/or scale from the source to the target bone. Ticking all three options copies the transform entirely, while ticking none performs no operation.
Additionally, there is a Control Space option that can be set in the details panel of the node to dictate in which space the target bone should copy the source bone.
A note on the performance of Control Space
Since the node operates only on bones within the component, I believe the Control Space settings Component Space and World Space produce the visually same result.
They are computationally different though.
Internally, as of UE5.6, the code performs additional space conversions for any space other than Component Space, making World Space technically more expensive for the same result.