My stock TeX Live version 2021.20211217-1 is set up to produce A4 output by default.
Reproduce:
1) Create mwe.tex containing
\documentclass{article}
\pagestyle{empty}
\usepackage{pst-node}% letter with this, A4 without this. pstricks or pst-all would do as well
\begin{document}
test
\end{document}
2) Run
latex mwe
dvipdf -dALLOWPSTRANSPARENCY mwe.dvi
pdfinfo mwe.pdf
3) Observe that the resulting PDF has letter format. If we don't use pst-node/pstricks/pst-all, we get A4 as usual.
Simply using a drawing package and not specifying anything about the paper (such as the class options a4paper or letterpaper) should not incur a deviation from the system-default paper format.