Include multiple PDFs with different size and additional text on one page

My suggestion is use any document type and just mess with the margins. For the other features you will find simple answers anywhere, that's one of the multiple possible choices:

documentclass[]{article}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
usepackage{vmargin} % para editar los margenes
setpapersize{USletter}
setmargins{2cm}% margen izquierdo
{1.5cm}     % margen superior
{17cm}      % anchura del texto
{23.42cm}   % altura del texto
{10pt}      % altura de los encabezados
{1cm}       % espacio entre el texto y los encabezados
{0pt}       % altura del pie de página
{1cm}       % espacio entre el texto y el pie de página
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
usepackage[demo]{graphicx}
usepackage{caption,subcaption}

begin{document}

centering Huge Title

begin{figure}[htbp]centering
    includegraphics[width=linewidth]{imagefile}
    caption{Figure 1 text}
end{figure}

begin{figure}[htbp]centering
    includegraphics[width=linewidth]{imagefile}
    Figure 2 text (but in text mode, not in caption)
end{figure}

begin{figure}[htbp]centering
    begin{subfigure}{0.2textwidth}            
        includegraphics[width=linewidth]{imagefile}
        caption{Figure 3 text}
    end{subfigure}
    begin{subfigure}{0.485textwidth}centering            
        includegraphics[width=linewidth]{imagefile}
        Figure 4 (in text mode)
    end{subfigure}
    begin{subfigure}{0.3textwidth}            
        includegraphics[width=linewidth]{imagefile}
        caption{Figure 5 text}
    end{subfigure}
    caption{Figures 3, 4 y 5}
end{figure}
    
end{document}

and I get something like this