Open the App Store and install a music app such as Apple Music, Spotify, Amazon Music, or YouTube Music
Sign in to your account in the app
Search for the song, album, or playlist you want
Tap the Download button or the downward arrow icon
Wait for the download to finish
Open the Music app or your chosen app to access the downloaded music offline
To download music from a computer, connect your iPhone to a Mac or PC with a cable
On a Mac, use Finder to sync music to your iPhone
On a PC, use iTunes or the Apple Devices app to sync music to your iPhone
Select the music files you want to transfer
Click Sync or Apply to copy the music to your iPhone
Check that the music appears in your iPhone’s library or app for offline playback