What happened to my itunes app on my phone?

I just bought the Iphone 12 and had everything transferred from my iphone 6S Plus. I realize my ITUNES app is not on my new 12 or my 6S+. I also bought the new IPAD 8 and Itunes is now missing from that and my old ipad mini.

Please explain what happened to my Itunes App and how to get it back. i have playlists that i have worked hours to create and now i have no access.

Thank you!

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