JSFiddle - React, Tailwind, and code Playground

HTML

<form>
    <fieldset>
        <input type="number" name="" min="1" max="10" id="ordem-banner" pattern="">
        <label class="switch">
            <input type="checkbox" id="btn-ativa">
            <div class="slider round"></div>
        </label>
    </fieldset>
    <fieldset>
        <input type="submit" name="" value="Cadastrar">
    </fieldset>
</form>

JavaScript

var activeBtn = document.getElementById('btn-ativa');
var ordenadorBanners = document.getElementById('ordem-banner');
activeBtn.addEventListener('change', function() {
    ordenadorBanners.required = this.checked;
	/* Ou então assim:
    if (this.checked) ordenadorBanners.setAttribute('required', 'required');
    else ordenadorBanners.removeAttribute('required', 'required');
	*/
});