@mos_8502 As far as I know, it's not built into the protocol, so it would have to be special to that client /shrug
Like, originally (I think), people sent images over IRC via base64 encoding because it's text-based. Then, dcc file transfers and bots like Eggdrop let people share files more directly...
On the other hand: There's literally nothing stopping people from using Signal to do just about everything Discord does, as far as I can tell. (though it needs to divorce itself from phone #'s)