Legacy Key

See the section on sharing access to the key: How to add a Legacy Contact for your Apple ID - Apple Support

Included there is how to print the key (which will require an AirPrint printer, or add-on printer software, if using an iPhone or iPad) or to send the key via other means.

Are you the sender (aka pre-decedent) or the receiver (survivor)?

Regardless, you can view any keys on-file within your AppleID at:

Settings -> AppleID [Name] -> Password & Security -> Legacy Contact

See additional detail and additional links here:

How to add a Legacy Contact for your Apple ID – Apple Support (AU)

You are certainly welcome.

It’s important that the “receiver” fully understand his/her responsibilities.

Managing a decedent’s digital legacy - for many - is of sufficient importance that IMO any pre-designated executor should be one of the legacy contacts.