Great video:
https://www.youtube.com/watch?time_continue=101&v=tMGIgJAsJpwI have no experience with this, although I am thinking of putting my next few projects onto a streaming site. Your comment enticed me to do a bit of diggin. The video above goes a bit in-depth about LUFS and how it is used on different streaming platforms. Essentially (based on that video), track volume is either increased or decreased depending on how close it is to the streaming platform's preferred LUF level. The goal is to keep all tracks in a similar volume range. That being said, I would assume it would hold true for transferrals between pieces.
If you make sure your album is mastered evenly as a whole (and kept to a percieved level), I'm certain it will transfer over into Spotify with little issue, including switching between tracks.