#1. Use code to Code Injection – Footer

<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.7.0/jquery.min.js"></script>
<script>
$(document).ready(function(){
    $('<a class="header-custom-search" href="/search"><img src="https://assets.squarespace.com/universal/images-v6/icons/icon-searchqueries-20-light.png"/></a>').insertBefore('div#multilingual-language-picker-desktop');
});
</script>

#2. Result