<h1 class="cp_h1title">見出しテキスト</h1>

.cp_h1title {
  position: relative;
  display: flex;
  justify-content: center;/*左右中央配置*/
  align-items: center;/*上下中央配置*/
}
.cp_h1title:before {
  content: '';
  position: absolute;
  width: 150px;/*括弧の幅*/
  height: 2.5em;/*括弧の高さ*/
  border-radius: 50%;
  border: 2px solid #F48FB1;/*括弧の線の色と太さ*/
  border-left-color: transparent;
  border-right-color: transparent;
}