Navigate to the “Global Permissions” within the Jira System settings (Settings > System > Global permissions).
At the bottom, you will find
the “Deep Clone for Jira (Bulk Clone) global permission,
the “Deep Clone for Jira - Project Clone” global permission.
A user with this permissions will be able to access Deep Clone for Jira for all issues in all projects, no matter how project permissions are configured. All users have this permission per default.