\documentclass{article}
\usepackage[T1]{fontenc}
\usepackage[sfdefault]{FiraSans}
\usepackage{lipsum}
\begin{document}

\begin{center}\huge\bf Fira Sans
\end{center}


\section*{Regular}
\lipsum[1]

\section*{Italic}
\textit{\lipsum[2]}

\section*{Bold}

\textbf{\lipsum[3]}

\section*{Bold Italic}

\textbf{\textit{\lipsum[4]}}


\section*{Small Caps Regular}

\textsc{\lipsum[5]}

\section*{Small Caps Italic}
\textsc{\textit{\lipsum[6]}}

\section*{Light}
{\firalight \lipsum[7]}

\section*{Medium}
{\firamedium \lipsum[8]}


\section*{Light Italic}
{\firalight \textit{\lipsum[9]}}

\section*{Medium Italic}
{\firamedium \textit{\lipsum[10]}}

\section*{Default Numbers}

1234567890

\section*{Oldstyle Numbers}

{\firaoldstyle 1234567890}

\section*{Lining Numbers}

{\firalining 1234567890}

\section*{Tabular Numbers}

{\firatabular 1234567890}

\section*{Proportional Numbers}

{\firaproportional 1234567890}

\section*{Superior Numbers}

X{\sufigures 1234567890}


\end{document}
