With packages such as Nerd Icons and All The Icons you can use ’emoji’ icons in various places in Emacs; see the specific packages for details.
mu4e has support for these in its message-view, where it can use the
emojis to decorate the mime-types for attachments. You can enable this through
the variable mu4e-file-name-to-icon-function, which you can set to e.g.,
all-the-icons-icon-for-file or nerd-icons-icon-for-file name, for
All-the-Icons and Nerd-Fonts, respectively.