They will definitely ask a full copy of personal documents before processing your request. Cex.io has been a well-known crypto exchange for Ukraine-based crypto companies but they have slow support after the increasing popularity of crypto investment. No worries, the support team will reset the 2FA even if you have no access to the lost phone number/email/authentication app.
The best solution is to maintain a notebook to write you all the accounts credentials including Google Authentication codes and keep it always under you.
An even better option is to use a 2FA app such as Aegis, which allows you to export an encrypted database of all your shared secrets, which you could store on an offline medium such as a USB drive. Then, if you lose your phone and you need to recover your 2FA codes, it's as easy as downloading the app on your new phone and importing the back up.
I absolutely wouldn't recommend Authy. It is closed source. Your 2FA codes are stored in their servers. They collect a lot of information about you, including device information, email address, phone number, IP address, location, log in history, and more. If you lose access to your account, they require full KYC with copies of your ID to recover your account. This is an unnecessary security and privacy risk, for something you can do safely yourself as described above.
Damn I really used to think Authy is a goat of a 2FA app, especially after finding out how bad GA was after I lost one of the 2FA keys. Welp, I am wrong as it seems.
Btw, this aegis, I have never heard about it up until now. I looked it up right now and the reviews seem great thus far. I will check it out, thanks!
Dude you should make a thread of all useful/privacy friendly crypto-services cause I assure you dumbasses like me don't know a lot about it.
I also didn't know about the recovery process but not going to change the default 2FA app to another one. Authy has done an amazing job after losing access to the old Google Authenticator app which contained more than 30 private 2fa keys to online accounts. I am ready to share documents if the Authy team asks this for security reasons and proving identity by asking few questions.