[De12]

const images = document.querySelectorAll('div.content img');

for (let i = 0; i < images.length; i++) {
    const imgf = images[i];
    const arri = [imgf];
    let img = imgf.nextElementSibling;
    while (img?.tagName === 'IMG') {
        arri.push(img);
        img = img.nextElementSibling;
        i++;
    }
    if (arri.length > 1) {
        const gal = document.createElement('div')
        gal.className = 'gal';
        imgf.parentElement.replaceChild(gal, imgf);
        gal.append(...arri)
    }
    
}

<div class="col-12 text">
<img data-src="/uploads/posts/2021-11/1636154460_default-good-1.png" class="fr-fic fr-dii lazy-loaded" alt="" src="/uploads/posts/2021-11/1636154460_default-good-1.png">
<img data-src="/uploads/posts/2021-11/1636154460_default-good-1.png" class="fr-fic fr-dii lazy-loaded" alt="" src="/uploads/posts/2021-11/1636154460_default-good-1.png">
<img data-src="/uploads/posts/2021-11/1636154460_default-good-1.png" class="fr-fic fr-dii lazy-loaded" alt="" src="/uploads/posts/2021-11/1636154460_default-good-1.png"> 

test test 
<img data-src="/uploads/posts/2021-11/1636154460_default-good-1.png" class="fr-fic fr-dii lazy-loaded" alt="" src="/uploads/posts/2021-11/1636154460_default-good-1.png">
<img data-src="/uploads/posts/2021-11/1636154460_default-good-1.png" class="fr-fic fr-dii lazy-loaded" alt="" src="/uploads/posts/2021-11/1636154460_default-good-1.png">
		</div>

вот такой текст был, класс контейнера с .content на .text в начале менял.