JSFiddle - React, Tailwind, and code Playground

HTML

<form>
		<label for="placa">Placa:</label>
		<input type="text" class="placa">

		<label for="concessionaria">Concessionaria:</label>
		<input type="text" name="concessionaria" id="concessionaria">
</form>
<form>
		<label for="placa">Placa:</label>
		<input type="text" class="placa">

		<label for="concessionaria">Concessionaria:</label>
		<input type="text" name="concessionaria" id="concessionaria">
</form>
<form>
		<label for="placa">Placa:</label>
		<input type="text" class="placa">

		<label for="concessionaria">Concessionaria:</label>
		<input type="text" name="concessionaria" id="concessionaria">
</form>

JavaScript

$(".placa").on('input', function() {
$(this).closest('form').find('#concessionaria').val("jaja");
});