How to make a dump of my iPhone so as to make forensics
You can read about how the encryption is performed and how the AES keys are built in Apple's iOS Security Guide:

https://www.apple.com/business/site/docs/iOS_Security_Guide.pdf

In particular this describes that the key is not available to the application processor. It is only available within the Secure Enclave. This means that even though you know your password, you cannot rebuild the AES-key from it on a different computer.

This means that it is not possible to do what you want (i.e. dumping the raw disk contents and decrypting it on another computer using AES keys that you build from your own password on that computer).

In regards to dumping raw disk content, you can use the dd command if you want - but you cannot really use it for anything.