Resizing mid document followup

Question

This is a follow up to this, and is based on this.

Code:

\documentclass[12pt]{article}
\usepackage{float}
\usepackage[american,siunitx]{circuitikz}
\usepackage[margin=1in]{geometry} 
\begin{document} 
    \section*{Hello}
    Hello\newline
    \newpage
    \makeatletter
    \let\small\@undefined
    \let\footnotesize\@undefined
    \let\scriptsize\@undefined
    \let\tiny\@undefined
    \let\large\@undefined
    \let\Large\@undefined
    \let\LARGE\@undefined
    \let\huge\@undefined
    \let\Huge\@undefined
    \input{size10.clo}\makeatother
    \section*{Hello}
    This is small.
    \begin{figure}[H]
        \centering
        \begin{circuitikz}
            \draw(0, 0) to [V, v_= $v_g\left(t\right)$] ++(0, -3) ;
            \draw(0, 0) to [R, l^= $R$] ++(3,0) to [C, l^=$C$] ++(0, -3) -- ++(-3,0);
        \end{circuitikz}
        \caption{A simple low-pass filter.}
        \label{RCFilter}
    \end{figure}
    \noindent
    This is small.
\end{document}

Output:

So while I was able to resize the future page of the document perfectly, I realized that the top and left margins get overridden with the original settings. In this MWE, the first page's margins get reset as well, but in another file, the pages that have been resized has the left and top margin reset to the original settings, but the past pages' margins are unaffected. How can I resize the font for the future pages properly while leaving the margins untouched? I tried \clearpage as advised as well as \newpage, but it didn't work.

Edit: I modified the code and the output to make things clearer on what I meant.

Answer 1

So I managed to figure out how: since I am using the geometry package, I put the \restoregeometry command. Here is the code:

\documentclass[12pt]{article}
\usepackage{float}
\usepackage[american,siunitx]{circuitikz}
\usepackage[margin=1in]{geometry} 
\begin{document} 
    \section*{Hello}
    Hello\newline
    \newpage
    \makeatletter
    \let\small\@undefined
    \let\footnotesize\@undefined
    \let\scriptsize\@undefined
    \let\tiny\@undefined
    \let\large\@undefined
    \let\Large\@undefined
    \let\LARGE\@undefined
    \let\huge\@undefined
    \let\Huge\@undefined
    \input{size10.clo}\makeatother
    \restoregeometry
    \section*{Hello}
    This is small.
    \begin{figure}[H]
        \centering
        \begin{circuitikz}
            \draw(0, 0) to [V, v_= $v_g\left(t\right)$] ++(0, -3) ;
            \draw(0, 0) to [R, l^= $R$] ++(3,0) to [C, l^=$C$] ++(0, -3) -- ++(-3,0);
        \end{circuitikz}
        \caption{A simple low-pass filter.}
        \label{RCFilter}
    \end{figure}
    \noindent
    This is small.
\end{document}

Output:

It may not be noticeable, but if you add more content like section headers, things will become clearer.