Capo and transpose.
The chords
An example in B♭ major. Put in your song's chords.
Move it to another key
To suit a voice, or to play along with a recording. One fret is one semitone.
B♭ majorAs written
Or pick the major key
Play it easier
Capo 3
Play G, D, Em and C shapes. They sound as B♭, F, Gm and E♭.
Every capo, easiest first
Shapes in pencil are harder: barres, stretches or muted strings.
Capos go up to fret 7 here; higher up, the neck gets cramped and the sound thin.