Back in early 2020, There was a special event in Sw/Sh in which you could encounter Mewtwo in Max Raids. But that was ages ago, so the only ways to get Mewtwo right now is:
1. Transfer it from another game to Pokemon HOME and then transfer it into Sw/Sh, or by trading with another player in either HOME, Let's Go or Sw/Sh
2. Find it in a max lair in the Crown Tundra
I agree with you. Mewtwo is my absolute favourite Pokemon as well!
Hope I helped!