fonts.conf

<?xml version='1.0'?>
<!DOCTYPE fontconfig SYSTEM 'fonts.dtd'>
<fontconfig>
 <match>
  <test name="lang" compare="contains">
   <string>th</string>
  </test>
  <edit mode="prepend" name="family">
   <string>Noto Sans Thai</string>
  </edit>
 </match>
 <alias>
  <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>
 <dir>~/.fonts</dir>
</fontconfig>