Ancient debris and Netherite are the two latest innovations in Minecraft, with which you can create the most powerful objects and armor.
First, you need to build the Void Portal (14 obsidians), then go through it.
Go down to levels Y 13-17, where you can find several blocks of Ancient ruins. During excavations be careful and beware of evil mobs, lava and other dangers of the Void.
Once you have the Ancient rubble, it’s time to melt it into Netherite. You can do that with a blast furnace. Once you have four pieces of Netherite, you can combine them on a workbench with four gold bars to make a Netherite bar.
Finally, by getting a Neterite bar, you can combine it with any diamond tool to make an improved version of this material.