Create Block Layout Helper

namespace Vendor\Module\Helper;

class Data extends \Magento\Framework\App\Helper\AbstractHelper
{

    /**
     * @var \Magento\Framework\View\LayoutInterface 
     */
    protected $layout;


    /**
     * Data constructor.
     * @param \Magento\Framework\App\Helper\Context $context
     * @param \Magento\Framework\View\LayoutInterface $layout
     */
    public function __construct(
        \Magento\Framework\App\Helper\Context $context,
        \Magento\Framework\View\LayoutInterface $layout
    ) {
        $this->layout = $layout;
        parent::__construct($context);
    }


    /**
     * @return block $valueContent
     */
    public function getBlock() {

        $valueContent = $this->layout
            ->createBlock('Magento\Cms\Block\Block')
            ->setBlockId('my_identifier')
            ->toHtml();

        return $valueContent;

    }
}