css

.corner{
  width:32px;
  height:32px;
  background-color:green;
  margin-bottom:4px;
}

.corner-1{
  clip-path: path("M0 0.509766V32.5098H32C14.33 32.5098 0 18.1798 0 0.509766Z");
}

.corner-2{
  clip-path: path("M32 0.509766V32.5098H0C17.67 32.5098 32 18.1798 32 0.509766Z");
}

.corner-3{
  clip-path: path("M32 32V0H0C17.67 0 32 14.33 32 32Z");
}

.corner-4 {
  clip-path: path("M0 32V0H32C14.33 0 0 14.33 0 32Z");
}

html

<div class="corner corner-1"></div>
<div class="corner corner-2"></div>
<div class="corner corner-3"></div>
<div class="corner corner-4"></div>