Specify attachment default path per note

Global attachments path is /attach

New A note set /attach/abc
other note set /attach/z/xx/`

any plugins?

As far as I know, there is only one path to be set for attachments. Any other scheme would require a plugin, or use of other tools to get it into the correct path.

You can’t specify an arbitrary folder for each note, but you can store attachments in the same folder as the note or in a subfolder of that folder (which will always have the same name). Settings => Files & Links => “Default location for new attachments” Manage attachments - Obsidian Help