Create a zoom or enlarge image function without using jQuery

I need to create a zoom or enlarge function to make images on my website bigger in some way (like some popup or something similar) but I can't use jQuery.

The reason why I can't use it is because it somehow disables the dropdown function in my navbar (made with Bootstrap 4).

The web page is going to have multiple images and I want to apply the function to clicked or hovered one.

<img width="30%"  height="200px;" class="page-images" src="img1.jpg"/>
<img width="30%"  height="200px;" class="page-images" src="img2.jpg"/>
...

If someone could help that would be great. Thanks.