I picked two pieces that were in related keys:
I used Mixed In Key to find the keys. Then I simply used F minor chords that transitioned to A-flat major chords. “Spectral” is rather atonal, while “015” is quite tonal and warm-sounding. I wanted my bridge to sound like George Martin’s orchestral swell that connects “Revolution 9” and “Goodnight”.
My approach was quite simple. Part of that was because of a lack of time. I think a simple approach worked here, though.