\documentclass{article}
\font\smallheadfont=cmr10 at 10truept
\font\medheadfont=cmr10 at 10truept % would prefer cmr7
\font\logofont=cmdunh10 at 17.28truept
\font\tinylogofont=cmdunh10 at 12truept
\font\smlogofont=cmdunh10 at 14.4truept
\font\enormousfont=cmr10 at 100truept
\font\tenrm=cmr10 at 10truept
\font\fraktur=cmfrak at 20truept
\begin{document}

{\hrulefill}

{\tiny tiny font} 5pt

{\scriptsize scriptsize font} 7pt

{\footnotesize footnotesize font} 8pt 

{\small small font} 9pt

{\normalsize normalsize font} 10pt

{\large large font} 12pt

{\Large Large font} 14.4pt

{\LARGE LARGE font} 17.28pt

{\huge huge font} 20.74pt

{\Huge Huge font} 24.88pt

{\hrulefill}

{\bf bold font}

{\it italic font}

{\sl slanted font}

{\hrulefill}

{\smlogofont TEST of custom font}

{\enormousfont A B C}

{\fraktur ABCDEFGHIJKLMNOPQRSTUVWXYZ}

{\fraktur abcdefghijklmnopqrstuvwxyz}

\end{document}