<div id="fadingImage" class="image-styled"></div>

body {
  display: flex;
  align-items: center;
  justify-content: center;
  height: 100vh;
}
.image-styled {
  background-position: center;
  background-size: cover;
  background-image: url("https://images.unsplash.com/photo-1615568929336-ddfd93ce683a?ixid=MXwxMjA3fDB8MHxwaG90by1wYWdlfHx8fGVufDB8fHw%3D&ixlib=rb-1.2.1&auto=format&fit=crop&w=1526&q=80");
  display: flex;
  height: 75vmin;
  width: 75vmin;
  transition: background 0.5s linear;
}

const imageEl = document.getElementById("fadingImage");
const images = [
  "https://images.unsplash.com/photo-1615568929336-ddfd93ce683a?ixid=MXwxMjA3fDB8MHxwaG90by1wYWdlfHx8fGVufDB8fHw%3D&ixlib=rb-1.2.1&auto=format&fit=crop&w=1526&q=80",
  "https://images.unsplash.com/photo-1588250318414-908688966feb?ixlib=rb-1.2.1&ixid=MXwxMjA3fDB8MHxwaG90by1wYWdlfHx8fGVufDB8fHw%3D&auto=format&fit=crop&w=2089&q=80",
  "https://images.unsplash.com/photo-1524077410193-2f667f9ab09a?ixlib=rb-1.2.1&ixid=MXwxMjA3fDB8MHxwaG90by1wYWdlfHx8fGVufDB8fHw%3D&auto=format&fit=crop&w=1650&q=80"
];

window.setInterval(changePicture, 5000);
let i = 0;
function changePicture() {
  i++;
  if (i > images.length - 1) i = 0;
  imageEl.style.backgroundImage = `url(${images[i]})`;
}