But they shouldn't. The key you enter as a user is actually only half of the key needed to decrypt the data. The other half of the key is generated by the secure enclave when the device was first powered on. This part of the key alone should be impossible to brute force and is stored in tamper resistant flash memory on the secure enclave co-processor.

So you would need to break open the co-processor without destroying its contents and read the secure enclave key before any brute forcing could happen directly on the encrypted data.

And no you can't just try to brute force it by sending decryption requests to the secure enclave. The secure enclave itself implements a exponentially increasing lockout time and won't respond to decryption requests during it. [0]

[0] https://www.apple.com/in/business-docs/iOS_Security_Guide.pd...