img:hover {

transform: scale(1.1);

}
1.1 is a multiple

you need to write an animation
see https://daneden.github.io/ani. to find the animation effect you need

of course, you can also write an animation effect yourself

keyframes zoomLarge {
    from 0% {
        transform:scale(0)
    }
    
    50% {
        transform:scale(1.2)
    }
    
    to {
        transform:scale(0)
    }
}

add

animation:zoomLarge 5s 1;

I hope I can help you. Welcome to my official account of Wechat: Front-end Guide