The melody of Really Don’t Care by Demi Lovato runs 570 notes across 57 bars, 3:17 long in G at 122 beats per minute. The tab sits almost entirely in the first two frets, one note at a time — no chords to barre and no strumming pattern to keep up with. A piano backing track plays the chords and bass underneath, so the line you are learning sounds like the record even at half speed.
Prefer to strum and sing it instead? Really Don’t Care chords and lyrics.