to display title with this code you need to add one argument in this block xml with below parameter.

<argument name="at_label" xsi:type="string">Custom Heading or Title</argument>

in your code you need to add below changes.

<referenceBlock name="product.info.details">
    <block class="Magento\Catalog\Block\Product\View\Description" name="product.info.description"
           as="description" template="Magento_Catalog::product/view/attribute.phtml" group="detailed_info">
        <arguments>
            <argument name="at_call" xsi:type="string">getDescription</argument>
            <argument name="at_code" xsi:type="string">description</argument>
            <argument name="css_class" xsi:type="string">description</argument>
            <!-- add this line to display heading. -->
            <argument name="at_label" xsi:type="string">More Information</argument>
            <argument name="title" translate="true" xsi:type="string">More Information</argument>
            <argument name="sort_order" xsi:type="string">5</argument>
        </arguments>
    </block>
</referenceBlock>

Hope this solution help you to complete you task.

Note: Please make it right and add plus to this solution if this solution work for you.

Thank you.

to display title with this code you need to add one argument in this block xml with below parameter.

<argument name="at_label" xsi:type="string">Custom Heading or Title</argument>

in your code you need to add below changes.

<referenceBlock name="product.info.details">
    <block class="Magento\Catalog\Block\Product\View\Description" name="product.info.description"
           as="description" template="Magento_Catalog::product/view/attribute.phtml" group="detailed_info">
        <arguments>
            <argument name="at_call" xsi:type="string">getDescription</argument>
            <argument name="at_code" xsi:type="string">description</argument>
            <argument name="css_class" xsi:type="string">description</argument>
            <!-- add this line to display heading. -->
            <argument name="at_label" xsi:type="string">More Information</argument>
            <argument name="title" translate="true" xsi:type="string">More Information</argument>
            <argument name="sort_order" xsi:type="string">5</argument>
        </arguments>
    </block>
</referenceBlock>

To Edit title for existing tab you can use below code for change description title.

Add this code in catalog_product_view.xml file.

<referenceBlock name="product.info.description">
    <arguments>
        <argument name="title" translate="true" xsi:type="string">Custom Description</argument>
    </arguments>
</referenceBlock>

Hope this solution help you to complete you task.

Note: Please make it right and add plus to this solution if this solution work for you.

Thank you.