Your create underConstraction.js file in nextjs pages folder. copy my gist code and paste in your file.

underConstraction.js

export default function underConstraction() {
  return (
    <>
      <div className="bg-indigo-600">
        <div className="max-w-7xl mx-auto py-3 px-3 sm:px-6 lg:px-8">
          <div className="flex items-center justify-between flex-wrap">
            <div className="w-0 flex-1 flex items-center">
              <span className="flex p-2 rounded-lg bg-indigo-800">
                <svg
                  className="h-6 w-6 text-white"
                  xmlns="http://www.w3.org/2000/svg"
                  fill="none"
                  viewBox="0 0 24 24"
                  stroke="currentColor"
                  ariaHidden="true"
                >
                  <path
                    strokeLinecap="round"
                    strokeLinejoin="round"
                    strokeWidth="2"
                    d="M11 5.882V19.24a1.76 1.76 0 01-3.417.592l-2.147-6.15M18 13a3 3 0 100-6M5.436 13.683A4.001 4.001 0 017 6h1.832c4.1 0 7.625-1.234 9.168-3v14c-1.543-1.766-5.067-3-9.168-3H7a3.988 3.988 0 01-1.564-.317z"
                  />
                </svg>
              </span>
              <p className="ml-3 font-medium text-white truncate">
                <span className="md:hidden">
                  Our blog website is Coming Soon{" "}
                </span>
                <span className="hidden md:inline">
                  Our website is Coming Soon, follow us for update now!
                </span>
              </p>
            </div>
            <div className="order-3 mt-2 flex-shrink-0 w-full sm:order-2 sm:mt-0 sm:w-auto">
              <a
                href="#"
                className="flex items-center justify-center px-4 py-2 border border-transparent rounded-md shadow-sm text-sm font-medium text-indigo-600 bg-white hover:bg-indigo-50"
              >
                Twitter
              </a>
            </div>
            <div className="order-2 flex-shrink-0 sm:order-3 sm:ml-3">
              <button
                type="button"
                className="-mr-1 flex p-2 rounded-md hover:bg-indigo-500 focus:outline-none focus:ring-2 focus:ring-white sm:-mr-2"
              >
                <span className="sr-only">Dismiss</span>

                <svg
                  className="h-6 w-6 text-white"
                  xmlns="http://www.w3.org/2000/svg"
                  fill="none"
                  viewBox="0 0 24 24"
                  stroke="currentColor"
                  ariaHidden="true"
                >
                  <path
                    stroke-linecap="round"
                    stroke-linejoin="round"
                    strokeWidth="2"
                    d="M6 18L18 6M6 6l12 12"
                  />
                </svg>
              </button>
            </div>
          </div>
        </div>
      </div>

      <div className="relative bg-white overflow-hidden">
        <div className="max-w-7xl mx-auto">
          <div className="relative z-10 pb-8 bg-white sm:pb-16 md:pb-20 lg:max-w-2xl lg:w-full lg:pb-28 xl:pb-32">
            <main className="mt-10 mx-auto max-w-7xl px-4 sm:mt-12 sm:px-6 md:mt-16 lg:mt-20 lg:px-8 xl:mt-28">
              <div className="sm:text-center lg:text-left">
                <h1 className="text-4xl tracking-tight font-extrabold text-gray-900 sm:text-5xl md:text-6xl">
                  <span className="block xl:inline">
                    {" "}
                    Our Blog site is under{" "}
                  </span>
                  <span className="block text-indigo-600 xl:inline">
                    constraction
                  </span>
                </h1>
                <p className="mt-3 text-base text-gray-500 sm:mt-5 sm:text-lg sm:max-w-xl sm:mx-auto md:mt-5 md:text-xl lg:mx-0">
                  Anim aute id magna aliqua ad ad non deserunt sunt. Qui irure
                  qui lorem cupidatat commodo. Elit sunt amet fugiat veniam
                  occaecat fugiat aliqua.
                </p>
                <div className="mt-6 sm:mt-8 sm:flex sm:justify-center lg:justify-start">
                  <div className="rounded-md shadow">
                    <a
                      href="#"
                      className="w-full flex items-center justify-center px-8 py-3 border border-transparent text-base font-medium rounded-md text-white bg-indigo-600 hover:bg-indigo-700 md:py-4 md:text-lg md:px-10"
                    >
                      Notify
                    </a>
                  </div>
                </div>
              </div>
            </main>
          </div>
        </div>
        <div className="lg:absolute lg:inset-y-0 lg:right-0 lg:w-1/2">
          <img
            className="h-56 w-full object-cover sm:h-72 md:h-96 lg:w-full lg:h-full"
            src="https://images.unsplash.com/photo-1551434678-e076c223a692?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=2850&q=80"
            alt=""
          />
        </div>
      </div>
    </>
  );
}