magento 2 system configuration with a custom .phtml template?

Question

in system.xml:

<field id="custom_field" translate="label" type="text" sortOrder="1" showInDefault="1" showInWebsite="1" showInStore="1">
      <label>Custom Field</label>
      <source_model>Vendor\Module\Block\Adminhtml\System\Config\Custom</source_model>
</field>

Custom.php:

 namespace Vendor\Module\Block\Adminhtml\System\Config;
 use Magento\Framework\App\Config\ScopeConfigInterface;

class Custom extends \Magento\Config\Block\System\Config\Form\Field
{
protected $_template = 'Vendor_Module::system/config/custom.phtml';

const TEMPLATE = 'Vendor_Module::system/config/custom.phtml';

protected $_moduleManager;

/**
 *
 * @param \Magento\Backend\Block\Template\Context $context
 * @param ScopeConfigInterface $scopeConfig
 * @param \Magento\Framework\Module\Manager $moduleManager
 * @param \Magento\Framework\ObjectManagerInterface $objectmanager
 * @param array $data
 */
public function __construct(
    \Magento\Backend\Block\Template\Context $context,
    \Magento\Framework\App\Config\ScopeConfigInterface $scopeConfig,
    \Magento\Framework\Module\Manager $moduleManager,
    array $data = []
)
{
    $this->_scopeConfig     = $scopeConfig;
    $this->_moduleManager   = $moduleManager;
    parent::__construct($context, $data);
}

/**
 *
 * @return $this
 */
protected function _prepareLayout()
{
    parent::_prepareLayout();
    if (!$this->getTemplate()) {
        $this->setTemplate(static::TEMPLATE);
    }
    return $this;
}
/**
 * Retrieve element HTML markup.
 *
 * @param \Magento\Framework\Data\Form\Element\AbstractElement $element
 *
 * @return string
 */
protected function _getElementHtml(\Magento\Framework\Data\Form\Element\AbstractElement $element)
{
    $this->setNamePrefix($element->getName())
        ->setHtmlId($element->getHtmlId());

    return $this->_toHtml();
}

}

custom.phtml: As an example but more then that basically any html element

<div class="test">
    <p>
        Click <a href="#">here</a>
    </p>
</div>
<select name="custom" class="select admin__control-select"
        data-ui-id="select-groups-third-fields-custom-value">
    <option value="no">No</option>
    <option value="yes">Yes</option>
</select>
<input type="checkbox" name="test" />

<p>END</p>

Answer 1

I've manage to add by using frontend_model:

<field id="my_field" translate="label comment" type="text" sortOrder="10" showInDefault="1" showInWebsite="1" showInStore="0">
       <frontend_model>Vendor\Module\Block\System\Config\Custom</frontend_model>
       <label>Custom</label>
 </field>

Using this example:How to create a button in Magento 2 configuration section?