Select a bone other than the center
With a bone selected, right-click and select Auto Name from Name (left/right) to add L or R to the bone’s name.
With the bone selected again, right-click and click Symmetrize to create the bone on the opposite side.
In this article, I wrote about how to create a mirror of a bone.
This is short, but we hope it will be of some help to you to easily create the bone on the other side.
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