Simple Guide to Minecraft/Upgrading (After 1.20)

To obtain Netherite tools and armor, you must collect the diamond tool/armor variants of what you want to upgrade, Netherite Upgrade Simithing Templates, and Netherite. Netherite can be obtained from smelting Ancient Debris into Netherite Scrap. Combining four Netherite Scrap with 4 gold ingots creates one Netherite ingot. Netherite can also be found in bastion remnant loot chests. Netherite Upgrade Simithing Templates can be found in bastion remnants (guaranteed in treasure bastions).

With a Smithing Table (crafted with four planks and two iron), put your diamond tool/armor and combine it with Netherite ingots and Netherite Upgrade Simithing Templates to create Netherite variants of the tools and armors in the game.