local.conf

<?xml version="1.0"?>
<!DOCTYPE fontconfig SYSTEM "fonts.dtd">
<fontconfig>

 <alias>
   <family>sans-serif</family>
   <prefer>
     <family>Main sans-serif font name goes here</family>
     <family>Noto Color Emoji</family>
     <family>Noto Emoji</family>
   </prefer>
 </alias>

 <alias>
   <family>serif</family>
   <prefer>
     <family>Main serif font name goes here</family>
     <family>Noto Color Emoji</family>
     <family>Noto Emoji</family>
   </prefer>
 </alias>

 <alias>
  <family>monospace</family>
  <prefer>
    <family>Main monospace font name goes here</family>
    <family>Noto Color Emoji</family>
    <family>Noto Emoji</family>
   </prefer>
 </alias>
</fontconfig>