recovery key to unlock volume

Sounds like a T2 equipped Mac and you cannot get into Recovery Mode without the administrator password. Using CMD+R to boot will prompt for an administrator account that has a Secure Token associated with it. You cannot reach the Terminal in Recovery Mode until you have authenticated and unlocked the disk.

According to your profile, you have a MacBook Pro 2020 or later. Any MacBook Pro 2018 or later has T2 Security Chip. This means it's encrypted at the factory. The entire SSD is encrypted and the key to decrypt it is comprised of a public and private key pair. The private key is stored on the Secure Enclave within the T2 Security Chip. Private keys are to be kept secret. Think of the Secure Enclave like a black box that can be written to but not read from. All the critical secrets such as private keys are stored on the Secure Enclave. The public key is sent to the Secure Enclave and it replies either YES / NO if there is a match or not. When you type your password into a T2 equipped Mac it is run through an algorithm which determines the public key and sends that key to the T2 Secure Enclave which if it responds YES will unlock the encryption on the disk. If NO then after a few failed attempts, it will ask for the Recovery Key.

When setting up macOS there is a prompt to enable FileVault2. Turning on FileVault2 on an T2 equipped Mac merely generates a new public / private key pair and writes the private key to the Secure Enclave then provides the Recovery Key. Normally, the default is to save the Recovery Key to iCloud. But you can also choose to have the key displayed and it's your responsibility to write this key down and not lose it. There is no way to decrypt the drive without that Recovery Key.

If your Recovery Key is stored in iCloud you should be able to reset the password using your Apple ID. If you are seeing the prompt to type in a Recovery Key then it is possible that you either didn't click the prompt to reset using your Apple ID or you didn't save the Recovery Key to iCloud or this Mac is managed by an employer or educational institution. If the computer is managed then you should call your help desk who can provide the Recovery Key.

It is highly recommended that anyone with a T2 equipped Mac or the new Apple Silicon Macs turn on FileVault2 and save the Recovery Key to iCloud as it is the only way to reset your password or unlock your encrypted drive should the password fail and you are less likely to forget to write down the Recovery Key or lose it.

There is one last potential problem. During a macOS update, it may install a firmware update. While this update is being applied, the screen will go dark and there will be zero indications that the Mac is turned on. People have been known to think their Mac is stuck or hung and hold the power button. That is a very bad thing to do while updating the firmware. If the T2 Security Chip firmware update is interrupted, it is possible for the Secure Enclave to be wiped and that throws away ALL the private keys. If that happens there is no way to recover the data except to wipe out the Mac, re-install macOS and restore from a backup. If you do not have a backup then you lose all your data.

Is one asking about Set a firmware password on your Mac or the Computer Password ??

Intel Computer- Reset Computer Password

1 - Restart computer and immediately hold Command + r keys

2 - Top Tool Bar >> Utilities >> Terminal

3 - Type resetpassword as one word and no spaces

4 - Press Return key

5 - Follow the prompts and remember the New Password

M1 Computer - Apple Silicon

1 - Choose Apple menu > > Shut Down.

2 - Press and hold the power button on your Mac until you see “Loading startup options.”

3 - Click Options, then click Continue. 

4 - Top Tool Bar >> Utilities >> Terminal

5 - Type resetpassword as one word and no spaces

6 - Press Return key

7 - Follow the prompts and remember the New Password