Using LaTeX setstretch

LaTeX single spaces text by default.

\documentclass[10pt]{article}


\begin{document}
`Curiouser and curiouser!' cried Alice ...
\end{document}

LaTeX offers different line spacing options. The setspace package implements \setstretch.

\documentclass[10pt]{article}
\usepackage{setspace}
\setstretch{1.4}

\begin{document}
`Curiouser and curiouser!' cried Alice ...
\end{document}

The sort of scaling factor mirrors the idea of single- and double-spacing but differs from type leading.