In the prologue for The Legend of Zelda: Tears of the Kingdom, Link wields a Master Sword. Later on, you can reclaim that sword, but unfortunately unlike the prologue version, this one runs out of juice in about 10 minutes.
But, if you wanted to get yourself that unbreakable sword at any cost, now you can. This glitchy method was uploaded to YouTube by El Duende 05, and it’ll take around an hour of your time to pull off.
https://www.youtube.com/watch?v=GlVJarlWaTo/
Also, it can get messy with saves, as you’ll need to pile on other glitches to essentially teleport the Master Sword from the prologue into your save game. There are problems that can be caused with autosaves here though, so perhaps keep your main save untouched if you don’t want to risk messing it up.