I forgot my Authenticator code

A new two-factor authentication code is sent each time you attempt to log in. See the information in Two-factor authentication for Apple ID - Apple Support and in Get a verification code and sign in with two-factor authentication - Apple Support

I suspect you are asking about something other than Apple Two-Factor Authentication. If you have two-factor authentication turned on for your Apple ID you would have seen the code at least once when attempting to log in or you wouldn't be able to log in. For example, if you go to https://appleid.apple.com/ and click the "Sign In" near the top right of the screen you will be prompted for the two-factor code after you enter your Apple ID and password if your have two-factor turned on and you won't be able to gain access without receiving and entering the code.