You can try by creating an object of objectManager and should not use objectManager directly.

Use something like,

class Example extends \Magento\Framework\View\Element\Template
{
    private $_objectManager;
    public function __construct(
        \Magento\Framework\ObjectManagerInterface $objectmanager
    ){
        $this->_objectManager = $objectmanager;
    }

    public function getExample()
    {
        $customerSession = $this->_objectManager->create("Magento\Customer\Model\Session");
        if ($customerSession->isLoggedIn()) {
            $customerData = $customerSession->getCustomer()->getData();
            /*Your logic*/
        }
    }
}

You can try by creating an object of objectManager and should not use objectManager directly.

Use something like,

class Example extends \Magento\Framework\View\Element\Template
{
    private $_objectManager; 

    public function __construct(
        \Magento\Framework\ObjectManagerInterface $objectmanager
    ){
        $this->_objectManager = $objectmanager;
    }

    public function getExample()
    {
        $customerSession = $this->_objectManager->create("Magento\Customer\Model\Session");
        if ($customerSession->isLoggedIn()) {
            $customerData = $customerSession->getCustomer()->getData();
            /*Your logic*/
        }
    }
}