How can I regain access to my locked iCloud account?

A few years ago, my iCloud account was locked for security reasons, so I am unable to access it and have a new account. However, I still have photos and other documents I would like to recover from that account. My old phone is also iCloud locked to that account. However, when going to iforgot.apple.com, I was asked to 1. Send an unlock email, or 2. Answer security questions. I am not signed into the email address, so that isn’t an option. When clicking on “answer security questions,” it asked me to enter my birthdate. However, my real birthday is not the one entered into the account, so I cannot go any further than that screen. There is not an option to reset my security questions.

Is there any possible way I can sign in to this email to view the unlock instructions (even through a different app or service, i.e. manually entering the domain information, etc) or is contacting Apple Support the only way to regain access to the account?

Thanks in advance for any advice!