<div class="bg">
  <button class="button">
  Lorem ipsum dolor?
</button>
</div>

.bg {
  background: url(https://www.industrialempathy.com/img/remote/ZiClJf-1920w.jpg);
  height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
}

.button {
  font-size: 50px;
  font-weight: bold; 
  mix-blend-mode: screen;
  position: relative;
}
.button::before {
  content: '';
  position: absolute;
  left: 0;
  top: 0;
  right: 0;
  bottom: 0;
  background: white;
  mix-blend-mode: overlay;
}