<div class="marketeer-icon-wrapper">
  
  <div class="red-square"></div>
    <div class="white-square"></div>
  
</div>

.marketeer-icon-wrapper {
  --size: 30px; /* muda aqui e tudo escala */
  
  position: relative;
  width: var(--size);
  height: var(--size);
  display: flex;
  justify-content: center;
  align-items: center;
  overflow: hidden;
}

.red-square {
  width: 100%;
  height: 100%;
  background-color: var(--primary);
}

.white-square {
  position: absolute;
  width: calc(var(--size) * 0.7071);
  height: calc(var(--size) * 0.7071);
  top: 50%; /* vamos posicionar o vértice inferior no centro */
  left: 50%;
  transform: translate(-50%, -125%) rotate(45deg); /* centraliza e sobe metade */
  background-color: #ffffff;
  z-index: 5;
}