Mastering.com's Logic Pro walkthrough covers the Transposer MIDI plugin, a quick way to shift and reshape MIDI without touching the notes themselves.
Transpose moves everything up or down by up to two octaves. Scale Quantize snaps those notes into a key and scale you choose, useful for auditioning a different key before committing.
There's a real gotcha worth knowing: the quantizing algorithm typically pulls notes down to fit the scale rather than pushing them up. Going major to minor sounds natural, but minor to major can land oddly since notes that should move up get shoved down an octave instead.
Signal flow matters too. Transpose happens before Scale Quantize by default, but flipping that order, quantizing first, then transposing, gives cleaner, more transparent results.