Tearable Poster In

\documentclass[a4paper,12pt]{article}

% ================================================================================
% 									Parameters
% ================================================================================

% Number of tabs at the bottom of the page
\newcommand{\numTabs}{12}

% Page Width (A4 = 21cm)
\newcommand{\pageWidth}{21}

% Margins in cm (Left and Right)
\newcommand{\marginLeft}{2}
\newcommand{\marginRight}{2}

% Bottom margin in cm (It matches the height of the tabs)
\newcommand{\marginBottom}{2.5}

% Vertical distance from the bottom of the tabs in cm
\newcommand{\tabTextYOffset}{0.1}

% Radius of the box corners in mm
\newcommand{\boxarc}{6}

%  Width of the box corners in pt
\newcommand{\boxlinewidth}{3}

% Main text of the Announce 
\newcommand{\mainTitle}{Main Title}
\newcommand{\mainDesc}{Main description}
\newcommand{\mainDetails}{Main details}
\newcommand{\mainContact}{Call: \underline{Phone number}}

% Text on tabs
\newcommand{\tabText}{Contact: Phone number}

% ================================================================================
% 								End	Parameters
% ================================================================================
\usepackage[margin=\marginLeft cm, right=\marginRight cm, left=\marginLeft cm, bottom=\marginBottom cm]{geometry}
\usepackage{tikz}
\usepackage{lmodern}
\usepackage{rotating}
\usepackage[most]{tcolorbox}
\pagestyle{empty}

\begin{document}
	
	\begin{center}
		\begin{tcolorbox}[
			colframe=black,
			colback=white,
			arc=\boxarc mm,
			boxrule=\boxlinewidth pt,
			width=0.93\textwidth,
			left=8mm, right=8mm,
			top=6mm, bottom=6mm,
			enhanced,
			]
			\begin{center}
				\Huge\bfseries
				\mainTitle
				
				\vspace{0.5cm}
				\large
				\mainDesc
				
				\vspace{0.6cm}
				%\normalsize
				\mainDetails
			\end{center}
			\vspace{1cm}
			\begin{center}
				\textbf{\mainContact}
			\end{center}
		\end{tcolorbox}
	\end{center}
	
	\vfill
	
	% Tabs at bottom
	\noindent
	\begin{tikzpicture}[remember picture, overlay]
		% Page width
		\pgfmathsetmacro{\usablewidth}{\pageWidth-\marginLeft-\marginRight}
		% Height tabs
		\pgfmathsetmacro{\tabheight}{\marginBottom}
		% Y of line (at \marginBottom from bottom)
		\pgfmathsetmacro{\lineY}{\marginBottom}
		% Cicle for tabs
		\foreach \i in {0,...,\numexpr\numTabs-1} {
			\pgfmathsetmacro{\xstart}{\i*(\usablewidth/\numTabs)}
			\pgfmathsetmacro{\xcenter}{\xstart+0.5*(\usablewidth/\numTabs)}
			% Vertical dashed line
			\draw[dashed] ({\xstart},{\lineY}) -- ({\xstart},-2);
			% Rotated text centered in each tab, with a parametric offset from the bottom
			\node[rotate=90, anchor=south, font=\small]
			at ({\xcenter},{\tabTextYOffset})
			{\tabText};
		}
		% Dashed line to the right of the first tab to close it
		\draw[dashed] ({\usablewidth},{\lineY}) -- ({\usablewidth},-2);
		% Horizontal dividing line
		\draw[thick] (0,{\lineY}) -- ({\usablewidth},{\lineY});
	\end{tikzpicture}
\end{document}