Can you just use the iPhone 4 to listen to music?

Yes, you can use the iphone 4 to listen to music. It has a built-in music player app that can play songs stored on the device or stream music through apps like Apple Music and Spotify. Additionally, it supports headphones and external speakers for audio output. However, be aware that the iphone 4 may not support some newer apps or features due to its outdated hardware and software.