Formulário de pesquisa com ícone

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Formulário de pesquisa com ícone estilizado com #bootstrap 5. Mais campos podem ser adicionados conforme necessidade.

Neste exmplo foram utilizadas as classes card, shadow e #form-control

formulário de pesquisa com bootstrap 5

<!DOCTYPE html>
<html lang="pt-br" dir="ltr">

<head>
  <meta charset="utf-8">
  <title></title>
  <meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
  <link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/bootstrap-icons@1.9.1/font/bootstrap-icons.css">
  <link href="https://cdn.jsdelivr.net/npm/bootstrap@5.1.3/dist/css/bootstrap.min.css" rel="stylesheet" integrity="sha384-1BmE4kWBq78iYhFldvKuhfTAU6auU8tT94WrHftjDbrCEXSU1oBoqyl2QvZ6jIW3" crossorigin="anonymous">
</head>

<body>
  <!-- created by @BrCodeSnippets -->
  <div class="container mt-3 pt-3">

    <div class="row mb-2">
      <div class="col-12 col-sm-12">
        <h1 class="text-center fw-bolder">Bootstrap 5 - search form</h1>
      </div>
    </div>
    <form class="row g-3">
      <div class="col-12">
        <div class="card bg-secondary bg-gradient shadow border-0">
          <div class="card-body p-0">
            <div class="row g-0">
              <div class="col-12">
                <h5 class="card-title p-3 text-white"><i class="bi bi-search"></i> Search</h5>
              </div>
              <div class="col-12 col-sm-12 col-lg-5">
                <div class="bg-white p-3">
                  <input class="form-control" type="text" name="" value="" placeholder="input a text">
                </div>
              </div>
              <div class="col-12 col-sm-10 col-lg-5">
                <div class="bg-white p-3">
                  <select class="form-select" aria-label="Default select example">
                    <option selected>Open this select menu</option>
                    <option value="1">One</option>
                    <option value="2">Two</option>
                    <option value="3">Three</option>
                  </select>
                </div>
              </div>
              <div class="col-12 col-sm-2">
                <div class="bg-white p-3">
                  <button class="btn btn-info w-100" type="button" name="button"> <i class="bi bi-search"></i></button>
                </div>
              </div>
            </div>
          </div>
        </div>
      </div>
    </form>
  </div>
  <script src="https://cdn.jsdelivr.net/npm/bootstrap@5.1.3/dist/js/bootstrap.bundle.min.js" integrity="sha384-ka7Sk0Gln4gmtz2MlQnikT1wXgYsOg+OMhuP+IlRH9sENBO0LRn5q+8nbTov4+1p" crossorigin="anonymous"></script>
</body>

</html>

Demonstração