Input Form Frist Later Automatic Capital Code

<input type="text" id="first_name" name="first_name" placeholder="First Name" class="input-field" oninput="capitalizeFirstLetter(this)" required>

Add This Line oninput="capitalizeFirstLetter(this)"

And Add This Java Code

<script>
function capitalizeFirstLetter(input) {
    let words = input.value.split(' ');
    for (let i = 0; i < words.length; i++) {
        words[i] = words[i].charAt(0).toUpperCase() + words[i].slice(1);
    }
    input.value = words.join(' ');
}
</script>