Adjusting the paragraph margin in subsection

Question

It might be a simple yet a silly question but it keeps bugging me for days. Base on my code:

\documentclass[a4paper, 11pt]{article} 
\usepackage[margin=2cm]{geometry} % changes the margin
\usepackage{enumitem}
\usepackage{titlesec}
\usepackage{indentfirst}
\usepackage{blindtext}

\renewcommand\thesection{\Alph{section}.}
\renewcommand\thesubsection{\arabic{subsection}.}
\titleformat{\section}
{\normalfont\fontsize{11}{.5em}\bfseries}{\thesection}{.5em}
    {}
\titleformat{\subsection}
{\normalfont\fontsize{11}{.5em}\selectfont}{\thesubsection}{.5em}
    {}
\titlespacing % starred version: first paragraph is not indented
{\subsection} % <command>
{1em} % <left>
{.4em} % <before-sep>
{.3em} % <after-sep>

\begin{document}

\section{Introduction}
\subsection{Subsection One}
    \begin{itemize}  [leftmargin=1.3cm,topsep=0pt,itemsep=0pt,parsep=0pt,partopsep=0pt]
        \item some item here and there
        \item some item here and there
    \end{itemize}

\subsection{Subsection Two}
\setlength\parindent{.85cm} \blindtext

\end{document}

And it resulted in this picture

My question is, how can I adjust the paragraph margin parallel with the subsection number? and not the section number?

Answer 1

Is this what you want? It all relies on the \llap command, which inserts its argument to the left of the current point on the line without moving the latter.

\documentclass[a4paper, 11pt]{article}
\usepackage[margin=2cm]{geometry} % changes the margin
\usepackage{enumitem}
\usepackage{titlesec}
\usepackage{indentfirst}
\usepackage{blindtext}

\renewcommand\thesection{\Alph{section}.}
\renewcommand\thesubsection{\arabic{subsection}.}
\titleformat{\section}
{\normalfont\fontsize{11}{.5em}\bfseries}{\llap{\thesection\hskip0.67em}}{0em}
    {}
\titleformat{\subsection}
{\normalfont\fontsize{11}{.5em}\selectfont}{\thesubsection}{.5em}
    {}
\titlespacing % starred version: first paragraph is not indented
{\subsection} % <command>
{0em} % <left>
{.4em} % <before-sep>
{.3em} % <after-sep>

\begin{document}

\section{Introduction}
\subsection{Subsection One}
    \begin{itemize} [leftmargin=1.3cm,topsep=0pt,itemsep=0pt,parsep=0pt,partopsep=0pt]
        \item some item here and there
        \item some item here and there
    \end{itemize}

\subsection{Subsection Two}
\setlength\parindent{.85cm} \blindtext

\end{document}