basic-addon1

html bootstrap5 Sample

入力コントロールの前にアドオンを配置：input-group-prepend

@ 
  <div class="input-group">
    <div class="input-group-prepend">
      <span class="input-group-text" id="basic-addon1">@</span>
    </div>
    <input type="text" class="form-control" placeholder="ユーザー名" aria-label="ユーザー名" aria-describedby="basic-addon1">
  </div>

入力グループ ボタン付きアドオン：input-group-append

  <div class="input-group mb-3">
    <input type="text" class="form-control" placeholder="検索キーワード" aria-label="検索キーワード" aria-describedby="basic-addon1">
    <div class="input-group-append">
      <button class="btn btn-secondary" type="button">検索</button>
    </div>
  </div>
  <div class="input-group mb-3">
    <div class="input-group-prepend">
      <button class="btn btn-secondary" type="button">好き</button>
    </div>
    <input type="text" class="form-control" placeholder="商品名" aria-label="商品名" aria-describedby="basic-addon2">
    <div class="input-group-append">
      <button class="btn btn-secondary" type="button">嫌い</button>
    </div>
  </div>

ナビバーの中に入力グループ

  <nav class="navbar navbar-dark bg-dark">
    <form class="form-inline">
      <div class="input-group">
        <div class="input-group-prepend">
          <span class="input-group-text" id="basic-addon1">@</span>
        </div>
        <input type="text" class="form-control" placeholder="ユーザー名" aria-label="ユーザー名" aria-describedby="basic-addon1">
      </div>
    </form>
  </nav>