2FA backup codes

There's no option to use backup codes for your 1Password account 2FA, and they've https://1password.community/discussion/89654/2fa-backup-codes there is no intention to add them unfortunately.

What you can do instead is, at the time you set up your 2FA via the TOTP QR code, print or save that QR code itself (or scan it into multiple authenticator apps).

I would recommend storing it separate from your Emergency Kit, but in a location that is equally safe/secure.

If the 2FA QR code is no longer on your screen and you want to do this, you will need to disable 2FA and re-enable it (noting that any places you scanned your old QR code in, need to be updated).

If you are completely locked out of 2FA, you can contact support. After verifying you through some specific details that only the account holder would know, they reset 2FA on your account.
This of course does not help if you are dead and you wanted your family to be able to log into your 1Password, in which case you would need to not have 2FA on your account, or do like the above and have the 2FA QR code stored safely.