Можно так
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Document</title>
</head>
<body>
<input oninput="checkParams();" id="osn_opti_special">
<input id="opti_special">
<input id="opti_special">
<input id="opti_special">
<input id="opti_special">
<input id="opti_special">
<input id="opti_special">
<input id="opti_special">
<input id="opti_special">
<script>
function checkParams() {
var name = document.getElementById('osn_opti_special').value;
document.querySelectorAll('[id="opti_special"]').forEach(function(input) {
input.value = name;
});
}
</script>
<style>
input { display: block; }
input:first-child { margin-bottom: 1em; }
</style>
</script>
</body>
</html>
Но правильней будет конечно же с class