@keyframes

p {
  animation-duration: 25s;
  animation-name: slidein;
}

@keyframes slidein {
  from {
    margin-left: 100%;
    width: 300%;
  }
  75% {
    font-size: 300%;
    margin-left: 25%;
    width: 150%;
  }

  to {
    margin-left: 0%;
    width: 100%;
  }
}