FWIW:
DISCLAIMER: I have not tried these commands on current versions of Mail running on macOS.
Proceed at your own risk.
Circa 2013, terminal commands could be used to tell Apple Mail running on then-current versions of OS X how YOU wanted Mail to display attachments ON YOUR DEVICE.
The command to disable in-line attachments (attachments appear as icons)
defaults write com.apple.mail DisableInlineAttachmentViewing 1
The command to (re-)enable in-line attachments once disabled (attachments appear as documents or images displayed in-line)
defaults write com.apple.mail DisableInlineAttachmentViewing 0
I've seen longer boolean variants of these commands, but if you remember that in binary,1 = ON, 0=OFF, it is easy to understand.