sudo apt install texlive-xetex
sudo apt-get install texlive-lang-all

pandoc test.md -s -o test.pdf --latex-engine=xelatex

---
title: Title text
geometry: margin=2cm
lang: ru
header-includes: |
    \newfontfamily{\cyrillicfont}{Arial}
    \newfontfamily{\cyrillicfontrm}{Arial}
    \newfontfamily{\cyrillicfonttt}{Arial}
    \newfontfamily{\cyrillicfontsf}{Arial}
---