<div class="container">
<div class="row">
  <div class="col-6 d-flex">
    <div class="block">
      Lorem ipsum dolor sit amet consectetur adipisicing elit. Nihil ullam, quos ipsam animi minima magni deleniti aliquam eaque sed corrupti fugit ut numquam sit obcaecati praesentium alias aspernatur molestiae? Quae.
    </div>
  </div>
  <div class="col-6 d-flex">
    <div class="block"></div>
  </div>
</div></div>

.block {
  background: red;
  flex-grow: 1;
  border-radius: 1rem;
  padding: 1rem;
}