\documentclass[aspectratio=169]{beamer}
\usepackage[frenchb]{babel}

\usepackage{beamerx}

\title[Subtitle]{Title}
\author{John Smith}

\begin{document}
  \begin{frame}{Stacked}
    \begin{block}{First}
      Text
    \end{block}
    \begin{block}{Second}
      Text
    \end{block}
    \begin{block}{Third}
      Text
    \end{block}
  \end{frame}

  \begin{frame}{Adjacent}
    \begin{columns}[t]
      \begin{column}{0.4\textwidth}
        \begin{block}{First}
          Text
        \end{block}
      \end{column}
      \begin{column}{0.3\textwidth}
        \begin{block}{Second}
          Text
        \end{block}
      \end{column}
      \begin{column}{0.3\textwidth}
        \begin{block}{Third}
          Text
        \end{block}
      \end{column}
    \end{columns}
  \end{frame}
\end{document}
