<section>
  <div>
    <h4>ellipse(50% 25%)</h4>
    <div class="box ellipse1"></div>
  </div>
  <div>
    <h4>ellipse(125px 100px at 50% 80%)</h4>
    <div class="box ellipse2"></div>
  </div>
</section>

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}
section {
  padding: 2vw;
  display: flex;
  gap: 2vw;
  flex-wrap: wrap;
  justify-content: center;
}
section > div {
  background-color: #eeeeee;
  position: relative;
  margin-top: 20px;
}
.box {
  width: 300px;
  height: 300px;
  background-image: url('https://fruntend.com/storage/photos/1/sunflowers.jpg');
  background-repeat: no-repeat;
}
.ellipse1 {
  clip-path: ellipse(50% 25%);
}
.ellipse2 {
  clip-path: ellipse(125px 100px at 50% 80%);
}
h4 {
  font-family: sans-serif;
  text-align: center;
  margin-bottom: 1vw;
  position: absolute;
  bottom: 100%;
  left: 0;
  right: 0;
}