On customer dashboard you see this

<https://github.com/magento/magento2/blob/ddf42caaf25311f10b23b95a92746f99943e045e/app/code/Magento/Customer/view/frontend/templates/account/dashboard/info.phtml#L23>

`<?= $block->getChildHtml('customer.account.dashboard.info.extra'); ?>`

Can you embed content into the template using this marker in an module?

Just add content to the marker. Not override the entire info.phtml.