Enlarge an image on click

I think what you are looking for is to make a kind of modal window. With Javascript you can do it, you just need to adapt the following code

// Get the modal
var modal = document.getElementById('myModal');

// Get the image and insert it inside the modal - use its "alt" text as a caption
var img = document.getElementById('myImg');
var modalImg = document.getElementById("img01");
var captionText = document.getElementById("caption");
img.onclick = function(){
    modal.style.display = "block";
    modalImg.src = this.src;
    captionText.innerHTML = this.alt;
}

// Get the <span> element that closes the modal
var span = document.getElementsByClassName("close")[0];

// When the user clicks on <span> (x), close the modal
span.onclick = function() { 
    modal.style.display = "none";
}

Source: How TO - Modal Images (w3schools)

You can change the image scale when clicked:

img = document.getElementById('myImg')
img.style.transform = 'scale(1.9)'