JSFiddle - React, Tailwind, and code Playground

HTML

<button class="class1" type="button">Btn</button>
<button class="class1" type="button">Btn</button>
<button class="class1 class2" type="button">Btn</button>

CSS

.bold {
    font-weight: bold;
}

JavaScript

$(".class1:not('.class2')").click(function () {
    $(this).toggleClass('bold');
});