Packages trajan
and fontenc
should be enough, as in this TUG article.
\documentclass{article}
\usepackage{trajan}
\usepackage[T1]{fontenc}
\begin{document}
{\trjnfamily %
TRAJAN EXISTS IN UPPERCASE ONLY. THE TRAJAN BUNDLE PROVIDES FONTS BASED ON THE CAPITALS CARVED ON THE TRAJAN COLUMN IN ROME IN $114$ AD. MANY TYPOGRAPHERS THINK THESE RANK FIRST AMONG THE ROMAN'S ARTISTIC LEGACY.
}%
Trajan exists in uppercase only. The trajan bundle provides fonts based on the capitals carved on the Trajan column in Rome in 114 AD. Many typographers think these rank first among the Roman's artistic legacy.
\end{document}
Beware because not all the characters that you may need are available in Trajan (I recommend to read the package guide).