_output.yml

bookdown::pdf_book:
  template: bookdown-koma.tex
  #includes:
  #  in_header: preamble.tex
  latex_engine: xelatex
  citation_package: biblatex # natbib is other option
  fig_caption: yes
  fig_height: 3.8
  fig_width: 6.3
  pandoc_args: [
    #"--top-level-division=chapter,"
    "--pdf-engine-opt=--shell-escape"
  ]
  keep_tex: yes
bookdown::bs4_book:
  css: bs4_style.css
  theme:
    primary: "#096B72"
  repo: https://github.com/rstudio/bookdown-demo
bookdown::epub_book: default