As you have mentioned that you are a fresher who has recently joined the organization, you should first confirm with the employee's supervisor or reporting authority whose probation period has been completed but has not yet received a confirmation letter. If the supervisor has already provided confirmation from their end, then you can proceed with the issuance of the confirmation letter after consulting with your HR head/manager. Before doing so, it is advisable to review the HR policy or confirmation policy of your organization.
Firstly, ensure that you have checked the above points, and then you may proceed with the issuance of the confirmation letter for the concerned employees.
Best Regards,
Vikas Ranjan