Magento 2 How to Display Country & State/Province Dropdown in Custom Frontend Form

First create block file and put below code in this file.

<?php
namespace NameSpace\ModuleName\Block;

class Form extends \Magento\Directory\Block\Data
{
    protected $_customerSession;

    public function __construct(
        \Magento\Framework\View\Element\Template\Context $context,
        \Magento\Directory\Helper\Data $directoryHelper,
        \Magento\Framework\Json\EncoderInterface $jsonEncoder,
        \Magento\Framework\App\Cache\Type\Config $configCacheType,
        \Magento\Directory\Model\ResourceModel\Region\CollectionFactory $regionCollectionFactory,
        \Magento\Directory\Model\ResourceModel\Country\CollectionFactory $countryCollectionFactory,
        \Magento\Customer\Model\SessionFactory $customerSession,
        array $data = []
    ) {
        $this->_customerSession = $customerSession->create();
        parent::__construct(
            $context,
            $directoryHelper,
            $jsonEncoder,
            $configCacheType,
            $regionCollectionFactory,
            $countryCollectionFactory,
            $data
        );
    }

    public function getCustomerLoggedIn()
    {
        if ($this->_customerSession->isLoggedIn()) {
            return $this->_customerSession->getCustomer();
        }
    }

    public function getFormData()
    {
        $data = $this->getData('form_data');
        if ($data === null) {
            $formData = $this->_customerSession->getCustomerFormData(true);
            $data = new \Magento\Framework\DataObject();
            if ($formData) {
                $data->addData($formData);
                $data->setCustomerData(1);
            }
            if (isset($data['region_id'])) {
                $data['region_id'] = (int)$data['region_id'];
            }
            $this->setData('form_data', $data);
        }
        return $data;
    }

    public function getConfig($path)
    {
        return $this->_scopeConfig->getValue($path, \Magento\Store\Model\ScopeInterface::SCOPE_STORE);
    }
}

Second create phtml file in your module

<?php
$countryList = $block->getCountries();
$regionList = $block->getRegion();
?>
<div>
    <form class="form-contact"
          action=""
          id="form-contact"
          method="post"
          data-hasrequired="<?php echo __('* Required Fields') ?>"
          data-mage-init='{"validation":{}}'>
         
        <fieldset class="fieldset contact-info">
            <div class="field region required">
                <label for="region_id" class="label"><span><?php echo __('State/Province:') ?></span></label>
                <div class="control">
                    <select id="region_id" name="region_id" title="<?php echo __('State/Province') ?>" class="validate-select" style="display:none;">
                        <option value=""><?php echo __('Please select a region, state or province.') ?></option>
                    </select>
                    <input type="text" id="region" name="region" value="<?php echo $block->getRegion() ?>" class="input-text <?php echo $block->escapeHtmlAttr($this->helper('Magento\Customer\Helper\Address')->getAttributeValidationClass('region')) ?>" style="display:none;">
                </div>
            </div>

            <div class="field country required">
                <label for="country" class="label"><span><?php echo $block->escapeHtml(__('Country:')) ?></span></label>
                <div class="control">
                    <?php echo $block->getCountryHtmlSelect() ?>
                </div>
            </div>
        </fieldset>
    </form>
</div>

<script type="text/x-magento-init">
    {
        "#country": {
            "regionUpdater": {
                "optionalRegionAllowed": <?= /* @noEscape */ $block->getConfig('general/region/display_all') ? 'true' : 'false' ?>,
                "regionListId": "#region_id",
                "regionInputId": "#region",
                "postcodeId": "#zip",
                "form": "#form-validate",
                "regionJson": <?= /* @noEscape */ $this->helper(\Magento\Directory\Helper\Data::class)->getRegionJson() ?>,
                "defaultRegion": "<?= (int) $block->getRegionId() ?>",
                "countriesWithOptionalZip": <?= /* @noEscape */ $this->helper(\Magento\Directory\Helper\Data::class)->getCountriesWithOptionalZip(true) ?>
            }
        }
    }
</script>