I\'d like to change text size for some page part, e.g. for verbatim block:
\\begin{verbatim}
\\end{verbatim
The use of the package \usepackage{fancyvrb} allows the definition of the fontsize argument inside Verbatim:
\begin{Verbatim}[fontsize=\small]
print "Hello, World"
\end{Verbatim}
The fontsize that you can specify are the common
\tiny
\scriptsize
\footnotesize
\small
\normalsize
\large
\Large
\LARGE
\huge
\Huge