Latex - Change margins of only a few pages

I've used this in beamer, but not for general documents, but it looks like that's what the original hint suggests

\newenvironment{changemargin}[2]{%
\begin{list}{}{%
\setlength{\topsep}{0pt}%
\setlength{\leftmargin}{#1}%
\setlength{\rightmargin}{#2}%
\setlength{\listparindent}{\parindent}%
\setlength{\itemindent}{\parindent}%
\setlength{\parsep}{\parskip}%
}%
\item[]}{\end{list}}

Then to use it

\begin{changemargin}{-1cm}{-1cm}

don't forget to

\end{changemargin}

at the end of the page

I got this from Changing margins “on the fly” in the TeX FAQ.

\par\vfill\break % Break Last Page

\advance\vsize by 8cm % Advance page height
\advance\voffset by -4cm % Shift top margin
% Start big page
Some pictures
% End big page
\par\vfill\break % Break the page with different margins

\advance\vsize by -8cm % Return old margings and page height
\advance\voffset by 4cm % Return old margings and page height

Use the "geometry" package and write \newgeometry{left=3cm,bottom=0.1cm} where you want to change your margins. When you want to reset your margins, you write \restoregeometry.

I was struggling a lot with different solutions including \vspace{-Xmm} on the top and bottom of the page and dealing with warnings and errors. Finally I found this answer:

You can change the margins of just one or more pages and then restore it to its default:

\usepackage{geometry}
...
... 
...
\newgeometry{top=5mm, bottom=10mm}     % use whatever margins you want for left, right, top and bottom.
...
... %<The contents of enlarged page(s)>
...    
\restoregeometry     %so it does not affect the rest of the pages.
...
... 
...

PS:

1- This can also fix the following warning:

LaTeX Warning: Float too large for page by ...pt on input line ...

2- For more detailed answer look at this.

3- I just found that this is more elaboration on Kevin Chen's answer.