<fontconfig>

<match>

  <test name="lang" compare="contains">

    <string>th</string>

  </test>

  <test name="family">

    <string>serif</string>

  </test>

  <edit name="family" mode="prepend">

    <string>Noto Serif Thai</string>

  </edit>

</match>

<alias>

  <family>Noto Serif Thai</family>

  <default>

    <family>serif</family>

  </default>

</alias>

</fontconfig>