|----Node A----|  |Node B|
|Node C||Node D|

documentclass[border=5mm]{standalone}
usepackage[latin1]{inputenc}
usepackage{tikz}
usetikzlibrary{shapes, arrows, arrows.meta}
usetikzlibrary{calc, arrows, fit, positioning, shapes.symbols, chains}
usetikzlibrary{decorations.markings, decorations.pathmorphing, decorations.pathreplacing}
pagenumbering{gobble} % Remove page number

begin{document}
% Define block styles
tikzstyle{block_large} = [rectangle, draw, text width=8cm, rounded corners, text height=0.4cm, text depth=1.25cm]
tikzstyle{block_medium} = [rectangle, draw, text width=4cm, rounded corners, text height=0.4cm, text depth=1.25cm]

    begin{tikzpicture}[node distance=1.5cm, auto, comment/.style={rectangle, inner sep=5pt}]
        % Draw nodes - first row
        node [block_large] (col1_row1) {
            textbf{Node A}\
            textit{Foo:} Bar\
            textit{Baz:} Qux
        };

        node [block_medium, right=1cm of col1_row1] (col3_row1) {
            textbf{Node B}\
            textit{Foo:} Bar\
            textit{Baz:} Qux
        };

        % Draw nodes - second row
        node [block_medium, below=0.1cm of col1_row1, anchor=north east] (col1_row2) {
            textbf{Node C}\
            textit{Foo:} Bar\
            textit{Baz:} Qux
        };
        node [block_medium, right=0cm of col1_row2] (col2_row2) {
            textbf{Node D}\
            textit{Foo:} Bar\
            textit{Baz:} Qux
        };
end{tikzpicture}

end{document}