So I have a reusable section elements with pre-defined patterns like Title, subtitle/tagline, and contents. I need something like Snippets but can put something inside it. I think it's Contents that I want but I wish I can use placeholders with it. How can I solve this?

All the sections has this kind of pattern:

<section>
    <header>
        <h2>Title Here</h2>
        <p>This tagline/subtitle is kinda dynamic</p>
        <p>Because it can be many "<p>" tags</p>
    </header>Snippets are not possible

    <div>
        Content here which is dynamic again.
    </div>
</section>

Wanted to make things easier cause I'm kinda making my "theme", even if I'm just the one who's using it, easy to use... in case I decided to make it an official theme.