Since you're using pdfLaTeX, you could load either the microtype or the letterspace package and employ the \textls* macro.
The amount of letterspacing (also known as "tracking") may be set via the optional argument of \textls*. In the example below, I've chosen a value of 100; feel free to change this setting as you see fit.

\documentclass{article}
\usepackage{letterspace} % or: \usepackage{microtype}
\newcommand\specialfont[1]{\textls*[100]{\MakeUppercase{#1}}}
\begin{document}
\specialfont{fancy letterspaced writing here}
FANCY LETTERSPACED WRITING HERE
\end{document}
\specialfontmacro use the same font face (albeit letter-spaced) as is in use in the surrounding text, or should a different font face be used? If so, which one? – Mico Apr 21 '17 at 04:31.logfile say? E.g., does it start with "This is pdfTeX, Version ..."? – Mico Apr 21 '17 at 04:38