storage: Do the songs downloaded remain on my phone after the playlist changes?

I have added a dozen playlists to my library on Apple Music, which are managed by Apple or other organizations, to be updated. When I go on a trip, I use Wi-Fi to download all those playlists before I leave (because Internet reception outside the city is bad). I am using the Apple Music application on an Android phone (Samsung Galaxy S8).

I have a decent storage space on my phone, and Apple Music currently occupies 11GB. However, I want to be cautious about how much storage space is being consumed. Are the songs that I downloaded from these playlists previously, in the previous version of the playlists, still stored on my phone or were they deleted? If they are on my phone, where are they? I probably would not use the old songs, because my main way of listening to them is to use these Apple playlists, as well as the "radio station creations". Therefore, I would like to delete old songs if they are not deleted automatically.

To clarify: I am not adding the songs from the playlists to my library. I'm just pressing the download button at the top of the playlist.