In Dragonflight Patch 10.1.5 – Fractures in Time, Players are able to create Legacy Tier Set Items in the Revival Catalyst, not just only the current Tier Sets. On the Patch 10.1.5 PTR, the Creation Catalyst in Zereth Mortis and the Revival Catalyst in Thaldraszus are being updated to accept legacy gear, allowing players to more easily acquire Tier Set models from Shadowlands Season 3 and Dragonflight Season 1.
Either Catalyst will allow you to put in a legacy piece of gear and turn it into a Tier Set piece, with no cost. This legacy piece of gear must drop from the correct raid in order to turn into the correct Tier piece: