SOURCE

const el = document.getElementById('box');
el.style.display = 'block';
const map = {none: 'block', block: 'none'};

setInterval(()=>{
  el.style.display = map[el.style.display];
}, 500);

<div id="box" style="display: none;" class="zoom">
    11112222233333
</div>

.zoom{
    animation: zoom 300ms ease-in-out;
}

@keyframes zoom{
    0% {
        opacity: 0;
        transform: scale(1.1);
    }
    100% {
        opacity: 1;
        transform: none;
    }
}