do i need an app on my iphone 11 so that i can download music from my laptop

If you have iTunes on your laptop and all of your music is indexed in iTunes then you don’t need anything else on the phone to download music. Note that iTunes can manage iTunes purchases, ripped CDs (and it can even rip them) and MP3s from other sources. To add music to iTunes just drag and drop the files to the iTunes app.

You can just sync music from your laptop to your phone using a USB cable or Wi-Fi→Sync your iPhone, iPad, or iPod using your computer - Apple Support

You can optionally get music players from other sources if you don’t want to use iTunes; for example the Amazon music player app.