How do I detect if my iPhone 15 Pro Max has been cloned?

iPhones cannot be cloned like other platforms.

1. SIM Cloning - Yes, but not without doing fraud. Someone tricks your mobile carrier into issuing a new SIM with your number. Once that happens:
   1. Your phone loses signal. The SIM that you have will not work. Inform your Carrier immediately.
   2. Their phone starts receiving your calls & OTPs
   3. They can reset banking/email passwords
   4. This doesn’t copy your photos or apps — just your number access.
2. iPhone Cloning - No, copying everything (apps, data, messages) without your password is extremely difficult because:
   1. iPhones use hardware-level encryption
   2. Data is tied to your device + Apple ID
   3. Without your passcode or Face ID, it’s nearly impossible
   4. Unless:
      1. You gave someone your Apple ID password
      2. You installed spyware
      3. Your iCloud is compromised

Otherwise, random remote “cloning” is mostly myth.

Keep the iPhone updated to the latest iOS always and never Jailbreak. That's it.

iOS / iPadOS devices cannot be hacked or infected with Viruses / Malware / Spyware *** unless you have intentionally downloaded spurious software or unauthorized apps directly from the internet and installed them on your device, and/or have Jailbroken. 

It (Hacking) also depends on how careful you are in sharing sensitive and valuable information pertaining to your iPhone such as Passcode, Password, etc with your friends and family members.

Be judicious when sharing the device's sensitive and valuable information with friends and family members.

**The primary reason for this is Sandboxing. All third-party apps are “sandboxed”, so they are restricted from accessing files stored by other apps or from making changes to the device. Sandboxing is designed to prevent apps from gathering or modifying information stored by other apps.

Security of runtime process in iOS and iPadOS - Apple Support

The sandbox on an iPhone is a security feature that creates a restricted environment for each app to run in isolation from other apps and the operating system. It is a core component of iOS's security architecture and plays a crucial role in making iPhones more secure.

If you doubt the authenticity of the information provided earlier, you have two alternatives:

1. Report the hacking incident to local law enforcement authorities and actively pursue the case.
2. Accept the credibility of the information; it is impervious to hacking. Just as some individuals hold unconventional beliefs, such as a flat Earth or moon landing denial, one has the freedom to believe in anything. The choice ultimately rests with you in this open and free world.