\documentclass[11pt, letterpaper, openany]{scrbook}
\usepackage[letterpaper, left=1in, right=1in, top=0.5in, bottom=0.5in, footskip=0.25in, marginparwidth=5em, bindingoffset=0.21in]{geometry}

\usepackage{marginnote}
\usepackage{sectsty}
\usepackage{ragged2e}
\usepackage{paracol}
\usepackage{fontspec}

\allsectionsfont{\centering}
\setlength\parindent{0pt}
\setlength{\columnsep}{1.25em}
\setlength{\parfillskip}{0pt}
\setlength{\tabcolsep}{1em}
\newfontfamily\leftfont[Path=default_fonts/EB_Garamond/, Ligatures=TeX, ItalicFont=EBGaramond-Italic.ttf, BoldFont=EBGaramond-Bold.ttf]{EBGaramond-Regular.ttf}
\newcommand{\daftitle}[1]{\centerfont{\huge{#1}}}


\raggedbottom

\begin{document}\begin{sloppypar}

\columnratio{0.5}
\begin{paracol}{1}
\fontsize{11}{13}\leftfont Quisque at nisi magna. Duis nec \textbf{lacus arcu. Morbi vel} fermentum leo. \textit{Pellentesque hendrerit sagittis vulputate.} \textbf{Fusce laoreet malesuada \textit{odio}} \textbf{, sit amet fringilla lectus ultrices porta} . Aliquam feugiat finibus turpis id malesuada. Suspendisse hendrerit eros sit amet tempor pulvinar. Duis velit mauris, facilisis ut tincidunt sed, pharetra eu libero. Aenean lobortis tincidunt nisi. \textbf{Praesent metus lacus, tristique} sed \textbf{porta non} , tempus id quam.\switchcolumn 

\end{paracol}
\end{sloppypar}\end{document}