Continuing A better long ≝ (defining equals, equals to by definition) without bumps, feeding
\documentclass{article}
\pagestyle{empty}
\usepackage{graphicx}
\newcommand*{\longEquals}{\mathrel{\scalebox{2}[1]{=}}}% Thanks to Marjin!
\begin{document}
\( = A \longEquals\)
\end{document}
to latex yields
in the DVI viewer xdvi. Both equality symbols come out equal, but the second equality should be twice as long. (Running the DVI output through dvips produces a long equality symbol as expected, though.) Any better long equality symbol that also shows up natively in the DVI?

\scaleboxachieves its effect using postscript commands that your DVI viewer probably does not evaluate. If you convert the dvi to ps (dvips) and view the ps file with a ps viewer, the length should have increased. If you intend to print the document, you will have to convert it to ps or pdf anyway. What prevents you from usingpdflatex,xelatexorlualatex? – gernot Feb 09 '23 at 19:56=\joinrel=leads to a bump in the middle at low resolutions; cf. https://tex.stackexchange.com/questions/674648 . – Feb 09 '23 at 20:00