If I remember correctly, when we set up email account security, in addition to asking for a phone number, google also asks us to set up a recovery email. If your primary email is hacked or your password is changed unexpectedly, it will send you a notification to the recovery email. please double check that you have them set up, if so check your alternate email inbox.
There is
[BEWARE] Sim Port Attack and 2 factor authentication for email but it depends on how you set up password for your email and whether as well as how you set up 2FA for your email. Recovery email is a one of last resort to recover your email.
I don't remember exactly reading somewhere if our email was hacked and we completely lost access. The last way we can do it is to send report to support and information including primary email, recovery email, phone number and most importantly, the date you created the email account.
Each email provider has different security mechanism as well as recovery method for users from Back up codes, 2FA or recovery (alternate) email. You must to read their guides or their warning/ reminder that regularly pops-up if you have yet set up enough security for your email.