Ok, hear me out. Not necessarily the absolute best three-track run, but just because it tends to be really overlooked and underrated, and because it's exactly three tracks long and the rest of the album isn't quite on the same level (I think I would find it too hard to pick any specific three tracks from my truly top-to-bottom favourite albums):
The starting three tracks of Red Velvet - The Velvet.
One of These Nights
Cool Hot Sweet Love
Light Me Up
This is still peak Velvet for me, even with the later more known and loved Velvet releases.