The following practice enables the Christian, in their lifetimes, to take an active role with Christ in salvaging the poor, unfaithful dead souls in hell. It is based on the premise that in order for Christ’s redemptive work of salvation to be complete, salvation must reach to all humans in all places of all times.
I’m not trying to dissuade you or anyone from praying for anything you believe is beneficial but to my knowledge praying for the dead is not biblical. These OT references are not for people in the afterlife as there is barely anything mentioned about afterlife in the OT plus 2nd Maccabees is extra biblical although the RCC uses it to justify praying for the dead.
I do think people can be saved after physical death through the LOF so if you think praying for them is beneficial then you should do what you think is right.