How I can open attached files

How do I open files attached to the notes? for example spreadsheets or app notes Apple notes? I have been able to attach it but not open it from Agenda

You can usually just tap them on iOS, or double click them on macOS.

Other options are available via the popover. On macOS, you get that by clicking, and on iOS, you get it by tap-and-hold on the attachment.

Kind regards,