Whether you're using the desktop or mobile Spotify app, you can easily download songs so you can listen to them offline.
How to Listen to Music Offline with Spotify: 11 Steps
How to Download Music to Apple Watch
How to Download Spotify for Offline Without Premium
Enjoy More Ways Than Ever to Use Spotify on Your Apple Watch—Now With Downloads — Spotify
How to Download Streaming Music and Listen Offline
How to download music from Spotify and listen to your favorite songs offline
How to Download Music from Spotify for Free
How to Download Songs on Spotify on Computer/Phone
How to Download Songs From Spotify for Offline Listening
How to Download and Listen to Music and Podcasts -- Offline and On the Go — Spotify