To move product variant to top of product page in Squarespace, above description, you can use this code to Website Tools > Code Injection > Footer.
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.7.0/jquery.min.js"></script>
<script>
$(document).ready(function(){
$('div.product-variants').insertBefore('div.ProductItem-details-excerpt-below-price');
});
</script>
