#1. Use this 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 href="/search" class="header-search"><img src="https://assets.squarespace.com/universal/images-v6/icons/icon-searchqueries-20-dark.png"/></a>').appendTo('nav.header-nav-list');
});
</script>
#2. Use this code to Custom CSS box
nav.header-nav-list {
align-items: center;
}
a.header-search {
margin-left: 1.5vw;
}
#3. Result
#4. If you want to change it to white color, use this to Custom CSS box
a.header-search {
filter: invert(1);
-webkit-filter: invert(1);
}