PHP parse dynamic content

For a particular project using PHP I need to parse content from a server action and display it as static content, similar to how Node would render the content.

For example, currently in this project content is rendered like this:

<h1>{{content1.data.page_data}}</h1>
<p>{{content3.data.page_data}}</p>

Whereas I need it to actually render as:

<h1>Welcome</h1>
<p>Page intro text goes here.</p>

Ideas on how to achieve this please.