How do I check if the width of the image is > 80% and if it is, set width to 80% in JavaScript?

My HTML is this:

Is It possible to animate the inside contents of an image, Not talking about elements inside of an image but the image objects things

I have a Frontend project where I have a banner image <img>.

How can I set the hitbox of an image to match exactly the image in javascript?

I’m new to javascript and I want to do something when the image is pressed but i need it to be exactly the hitbox of the image, not around it. Is there a way to do it?