I’ forgot my recovery key to my iCloud account

You're not talking to Apple.

If you still have a device logged into your account, you can generate a new recovery key. How to generate a recovery key - Apple Support

Otherwise, you'll need to find the key.

Using a recovery key is more secure, but it means that you’re

responsible for maintaining access to your trusted devices and your

recovery key. If you lose both of these items, you could be locked out

of your account permanently. With that in mind, it's important to keep

your recovery key in a safe place. You might want to give a copy of your

recovery key to a family member, or keep copies in more than one place.

That way you always have your recovery key when you need it.