dotfiles/config/fontconfig/conf.d/99-emoji.conf

<?xml version='1.0' encoding='UTF-8'?>
<!DOCTYPE fontconfig SYSTEM 'fonts.dtd'>
<fontconfig>
 <match>
  <test name="family">
   <string>sans-serif</string>
  </test>
  <edit name="family" binding="strong" mode="append">
   <string>Noto Serif</string>
   <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>
 <!-- Aliases for the other emoji fonts -->
 <!--<alias binding="strong">
  <family>Apple Color Emoji</family>
  <prefer>
   <family>Noto Color Emoji</family>
  </prefer>
 </alias>
 <alias binding="strong">
  <family>Segoe UI Emoji</family>
  <prefer>
   <family>Noto Color Emoji</family>
  </prefer>
 </alias>
 <alias binding="strong">
  <family>Emoji One</family>
  <prefer>
   <family>Noto Color Emoji</family>
  </prefer>
 </alias>-->
 <dir>~/.fonts</dir>
</fontconfig>