title: Header line break in Rmarkdown, change textsize after, included as a whole in TOC
body: <p>I want a header line break in Rmarkdown, after the break the text should appear smaller (it's the subtitle). The guy should appear in the table of contents as a whole (rather with author's name). 
  Here's my attempt where only the header appears in the TOC:</p>
  
  <pre><code>---
  title: "Untitled"
  output:
    pdf_document:
      toc: yes
  ---
  
  ```{r setup, include=FALSE}
  knitr::opts_chunk$set(echo = TRUE)
  ```
  
  # This is the header
  \vspace{-4mm}
  
  **This should be the subtitle after the line-break**
  
  \vspace{2mm}
  
  *Author's Name*
  
  \vspace{10mm}
  
  Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur.
  </code></pre>
  
  <p>Desired outcome something like this:
  <a href="https://i.stack.imgur.com/5idPV.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/5idPV.png" alt="enter image description here"></a></p>