input-group-lg

bootstrap5.css

bootstrap5.css
.input-group-lg > .form-control:not(textarea),
.input-group-lg > .custom-select {
  height: calc(1.5em + 1rem + 2px);
}
bootstrap5.css
.input-group-lg > .form-control,
.input-group-lg > .custom-select,
.input-group-lg > .input-group-prepend > .input-group-text,
.input-group-lg > .input-group-append > .input-group-text,
.input-group-lg > .input-group-prepend > .btn,
.input-group-lg > .input-group-append > .btn {
  padding: 0.5rem 1rem;
  font-size: 1.25rem;
  line-height: 1.5;
  border-radius: 0.3rem;
}
bootstrap5.css
.input-group-lg > .custom-select,
.input-group-sm > .custom-select {
  padding-right: 1.75rem;
}

html bootstrap5 Sample

入力グループのサイズ調整/大：input-group-lg

Large 
  <!-- 大サイズの入力グループ -->
  <div class="input-group input-group-lg">
    <div class="input-group-prepend">
      <span class="input-group-text" id="inputGroup-sizing-lg">Large</span>
    </div>
    <input type="text" class="form-control" aria-label="Large" aria-describedby="inputGroup-sizing-sm">
  </div>