Can I set a default sort?

There is a work around using custom Javascript, you should setup the sort attributes and add a sort button with the class ".fs_cmssort_button" that you set style to display:none .

‍
Then add the following script to the footer code.

‍

<script>
window.onload=function(){
document.querySelector(".fs_cmssort_button").click();
};
</script>