LaTeX – change spacing between lines and paragraphs

Customize space between lines and paragraphs

\setlength{\parskip}{1em} %set the spacing between paragraphs
\renewcommand{\baselinestretch}{1.4} %set the spacing between lines

LaTeX – choose margin size

Customize margin size

\usepackage{geometry}
\geometry{top=4cm, bottom=4cm, left=4cm , right=4cm}