\DocumentMetadata{
  lang        = en,
  pdfstandard = ua-2,
  pdfstandard = a-4f, %or a-4
  tagging=on,
  tagging-setup={math/setup=mathml-SE} 
}
\documentclass{article}
\usepackage{graphicx}
\usepackage{unicode-math}

\begin{document}
    \section{Foo}
    %
    This is a paragraph and \emph{this is in italics}
    \begin{figure}
        \centering
        \includegraphics[width=0.5\textwidth,alt={An image with the letter "A".}]{example-image-a}
        \caption{Here could be some figure}
    \end{figure}
    \begin{itemize}
        \item A list item.
        \item Another list item.
    \end{itemize}
    \begin{table}
        \centering
        \caption{This is a table}
        \tagpdfsetup{table/header-rows={1}}
        \begin{tabular}{ c | c }
            First row, first column and header & First row, second column and header\\\hline
            Second row, first column & Second row, second column
        \end{tabular}
    \end{table}
    \begin{equation}
        a^2 + b^2 = c^2
    \end{equation}
\end{document}