Copying is available to paid plan users only as there's a limit of 1 CJM, 1 IM, and 1 Persona per user on the free plan. So, if you're the one with a paid plan:
Open up the project with the Persona you want to copy.
Click on the COPY icon on the right of the Persona’s bar.
You’ll see a popup window where you can choose a target workspace and project.
To copy a Persona together with maps and personas that are linked to it, check the box near the “Copy all linked map/personas” option before confirming the copy action. To copy a Persona structure only, select the "Clear all content" option.
Copying Personas in Bulk
To copy Personas in bulk, check the boxes near them and hit COPY on the action bar.
Learn more about creating effective data-based personas at UXPressia Academy.