Answers for "how to smooth zoom in on hover"

css image hover zoom and rotate

img {
  transition: transform .7s ease-in-out;
}
img:hover {
  transform: rotate(360deg);
}

zoom animations in css

.zoom-in-out-box {
  margin: 24px;
  width: 50px;
  height: 50px;
  border:1px solid green;
  background: #f50057;
  animation: zoom-in-zoom-out 1s ease infinite;
}

@keyframes zoom-in-zoom-out {
  0% {
    transform: scale(1, 1);
  }
  50% {
    transform: scale(1.5, 1.5);
  }
  100% {
    transform: scale(1, 1);
  }
}