In the past, I used to use roboform and there was a nice feature to mention additional match field for a field.
If I have "email" as a field in identities then I can add additional match field like:
etc... so that it can work with any kind of new form I discover.
(I know 1password matches with many kinds of form with pre-defined fields but for custom fields and sometimes predefined fields as well, it will be very helpful)
1Password Version: Not Provided
Extension Version: Not Provided
OS Version: Not Provided
Sync Type: Not Provided