Restore

iCloud isn’t a backup, but whatever was on iCloud Drive is still there.

If your email is server-based (IMAP, Exchange, etc), it is still on the server.

Apps purchased from the App Store can be re-downloaded. Others will have to be reinstalled from the source.

Everything else is gone. If it is worth it, you could try file recovery software/service if it wasn’t a T2 or Apple Silicon Mac.

I agree with Barney-15E. The only data you will be able to recover would have to have been saved in an external location (Flash Drive, iCloud, Google Drive, Email Servers, etc.). Not sure if this will be useful, but if English is not your native language, Apple Support Communities is available in a variety of different languages.