How to use external html element/block inside UI form in magento 2

VendorName/ModuleName/view/adminhtml/ui_component/form.xml

htmlContent name="html_element"

block name="html_content_button_field"

arguments

argument name="template" xsi:type="string"

VendorName_ModuleName::load-button.phtml

argument

arguments

block

htmlContent

VendorName/ModuleName/view/adminhtml/templates/load-button.phtml