To change (required) to * in Form Block, 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>
window.addEventListener("load", (event) => {
$("span.description.required").html(function() {
return $(this).html().replace("(required)", "*");
});
});
</script>
<style>
span.description.required {
color: red !important;
opacity: 1 !important;
}
</style>