<div>
    <p>
        中央寄せテキスト<BR>2行目突入
    </p>
</div>
div {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 100%;
  height: 150px;
  background-color: skyblue;
  text-align: center; /* 2行目以降のテキストも中央寄せ */
}
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