I have an Office 365 email account configured as an Exchange account on my iPhone with iOS 13. When I archive an email, it is moved into the "Archive" folder (in English) even if my account is configured in Italian so that the official archive folder is spelled "Archivio" in Outlook. Everytime I archive an email on iPhone, the English folder is created and the email is moved there. How do I configure where to archive the email (eg: the right name of the archive folder)? Thank you.
Unfortunately, this is a function of Exchange, not the Mail.app or macOS.
The Exchange server is looking for a folder called "Archive" on the server itself so when you rename the folder, it can't find it so it creates a new one. Then Mail syncs with the Exchange server bringing the "Archive" folder back.
You'll have to file a bug report with Microsoft or just tolerate the English spelling of "Archivio."