JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.0/jquery.min.js"></script>
<form name="anmelden" method="post">

	<input type="radio" name="wechsel" id="wechselYes" value="1"  />
	<label for="wechselYes">Ja</label><br />

	<input type="radio" name="wechsel" id="wechselNo" value="2" checked="checked" />
	<label for="wechselNo">Nein</label><br><br>

	<label for="mailadresse">eMail Adresse</label>
	<input type="email" name="mailadresse" id="mailadresse" value="" /><br><br>

	<label for="name">Name</label>
	<input type="text" name="name" id="name" value="" /><br><br>

	<label for="ort">Ort</label>
	<input type="text" name="ort" id="ort" value="" />

	<br><br>
	<button id="abschicken" name="abschicken" >Abschicken</button>

</form>

JavaScript

$('input[name="wechsel"]').on("click", function () {
    if ($(this).val() == "1") {

		$('#ort').attr('required', 'required');
		$('#mailadresse').attr('required', 'required');
		$('#name').attr('required', 'required');
	
	} else {

		$('#ort').removeAttr('required');
		$('#mailadresse').removeAttr('required');
		$('#name').removeAttr('required');
	}
});