that doesn't delete messages from "Saved Messages" but it applies to all other old messages ONLY in that device, your other devices will have ALL messages
anyways, I think you are over-complicating your life, most mobile devices have plenty of storage these days, even in my several-years-old profile with my family it is only 1.3GB of storage used, and I don't use any deletion at all nor I care about cleaning up anything
Oblomov (npub1zgt…lpat) lgsp (npub12cc…udv3)