dots/.config/fontconfig/fonts.conf

<?xml version="1.0"?><!DOCTYPE fontconfig SYSTEM "fonts.dtd">
<fontconfig>
<!-- REQUIRES Noto fonts (along with Noto Color Emoji)
     run `fc-list | grep -i -e "noto sans" -e "noto serif" -e "noto color emoji"` to confirm and sudo apt-get install fonts-noto to install the fonts
-->

 <alias>
 <!-- Change the string in the family tag to whatever font -->
    <family>serif</family>
    <prefer><family>Noto Serif</family></prefer>
  </alias>
  <alias>
    <family>sans-serif</family>
    <prefer><family>Noto Sans</family></prefer>
  </alias>
  <alias>
    <family>sans</family>
    <prefer><family>Noto Sans</family></prefer>
  </alias>
  <alias>
    <family>monospace</family>
    <prefer><family>Noto Mono</family></prefer>
  </alias>

   <!-- This adds Noto Color Emoji to the font families sans, serif, sans-serif and monospace -->
  <match target="pattern">
        <test name="family"><string>monospace</string></test>
        <edit name="family" mode="append"><string>Noto Color Emoji</string></edit>
  </match>
  <match target="pattern">
        <test name="family"><string>sans</string></test>
        <edit name="family" mode="append"><string>Noto Color Emoji</string></edit>
  </match>

  <match target="pattern">
        <test name="family"><string>serif</string></test>
        <edit name="family" mode="append"><string>Noto Color Emoji</string></edit>
  </match>
  <!-- Discord loads the system's sans-serif font family, add Noto Color Emoji to it -->
  <match target="pattern">
        <test name="family"><string>sans-serif</string></test>
        <edit name="family" mode="append"><string>Noto Color Emoji</string></edit>
    </match>

   <!-- Add emoji generic family -->
  <alias binding="strong">
    <family>emoji</family>
    <default><family>Noto Color Emoji</family></default>
  </alias>

  <!-- Alias requests for the other emoji fonts -->
  <alias binding="strong">
    <family>Apple Color Emoji</family>
    <prefer><family>Noto Color Emoji</family></prefer>
    <default><family>emoji</family></default>
  </alias>
  <alias binding="strong">
    <family>Segoe UI Emoji</family>
    <prefer><family>Noto Color Emoji</family></prefer>
    <default><family>emoji</family></default>
  </alias>

<!-- Run "fc-cache -fv" after saving the file and kill and restart whichever app (like discord) and enjoy emoji -->

</fontconfig>