small input bootstrap code example

Example 1: large input box bootstrap 4

.form-control-sm
.form-control-lg

Example 2: input with bootstrap

<form>
  <div class="form-group">
    <label for="exampleInputEmail1">Email address</label>
    <input type="email" class="form-control">
    <small id="emailHelp" class="form-text text-muted">Hello, World</small>
  </div>
 </form>