How do I mass-delete all songs from iPhone 16?

Okay, so I got my iPhone 16 today. I had an iPhone11. I had my 1,000s of songs on the 11 directly from iTunes from my MacBook Pro from various physical albums and downloaded albums from torrents and such throughout many years. Nothing was from Apple Music.

I recently did get Apple Music, but I've yet to download anything from it.

So I got my iPhone 16 up and running; I eventually go to the music app and it seems my library transferred all over (great?!). I click on song after song, and they play (great?!) But then I notice in my settings that I only have 6 songs loaded on my new phone!? A lot more than 6 songs played when I clicked them.

Upon deeper diving I saw that many songs unplayable due to "this item is not synced across your devices" and "this item is not available in your country or region."

Is there a way to erase this entire library on my new phone all at once instead of going song by song clicked the 3 dots next to the title? If I do erase my entire library on my phone, will this erase my library on my MBP, despite my MBP library being build by me physically putting those songs on my laptop?

I love Apple devices, but I absolutely detest how they all work sometimes; this is surely one of those instances.

[Re-Titled by Moderator]