Increasing the size of the tikzpicture

Question

I am struggling to increase the size of the tikzpicture. When I load the code in an article or book class, the diagram is small. I have tried the scale command though the resulting output is very awful. Below is the MWE which is a solution provided to my question at Adding colored vertical dashed lines and removing circles on horizontal lines.

\documentclass{standalone}
\usepackage{pgfplots, pgfplotstable}
\usepackage{amsmath}
\makeatletter
\long\def\ifnodedefined#1#2#3{%
    @ifundefined{pgf@sh@ns@#1}{#3}{#2}%
}
\pgfplotsset{
    discontinuous/.style={
        scatter,
        scatter/@pre marker code/.code={
            \ifnodedefined{marker}{
                \pgfpointdiff{\pgfpointanchor{marker}{center}}%
                {\pgfpoint{0}{0}}%
                \ifdim\pgf@y>0pt
                \tikzset{options/.style={mark=none}}
                \draw [densely dashed,blue,thin] (O-|0,0) -- (0,0);
                %\draw plot [mark=*] coordinates {(marker-|0,0)};
                \else
                \tikzset{options/.style={mark=none}}
                \fi
            }{
                \tikzset{options/.style={mark=none}}

            }
            \coordinate (marker) at (0,0);
            \begin{scope}[options]
            },
            scatter/@post marker code/.code={\end{scope}}
    }
}
\makeatother
\begin{document}
\pgfplotsset{
    standard/.style={
        axis x line=middle,
        axis y line=middle,
        enlarge x limits=0.05,
        enlarge y limits=0.05,
        every axis x label/.style={at={(current axis.right of origin)},anchor=north west},
        every axis y label/.style={at={(current axis.above origin)},anchor=north east}
    }
}

{\centering
    \begin{tikzpicture}
        \begin{axis}[
            standard,
            clip=false,
            jump mark left,
            ymin=0,ymax=1,
            xmin=0, xmax=6,
            xlabel={$t$},
            xtick distance={.5},
            ylabel={$X(t)$},
            yticklabels={,,},
            xtick style={draw=none},
            ytick style={draw=none},
            %axis lines=middle,
            %axis line style={-},
            %ylabel near ticks,
            %xlabel near ticks,
            xticklabels={,,,$t_0$,,$t_1$,,,,$t_2$,$t_3$,,,$t_4$},
            every axis plot/.style={very thick},
            discontinuous,
            table/create on use/cumulative distribution/.style={
                create col/expr={\pgfmathaccuma + \thisrow{f(x)}}   
            }
            ]
            \path (0,0) coordinate (O);
            \addplot [orange] table [y=cumulative distribution]{
                x f(x)
                1 2/15
                2 1/5
                4 4/15
                4.5 1/3
                6 0
            };
        \end{axis}
    \end{tikzpicture}
    \par}

\end{document}