The native Music app is already optimized. Do not sideload a rogue IPA over the stock version.
Apple aggressively hunts for enterprise certificates used to sign these cracked apps. When you sideload an IPA using a free developer certificate, it will "revoke" within days. When this happens, the app crashes on launch, and all downloaded music (potentially gigabytes of it) becomes inaccessible. apple music ipa download extra quality