documentclass{article}
usepackage[T1]{fontenc}
usepackage{initials}

begin{document}

input Acorn.fd
newcommand*initfamily{usefont{U}{Acorn}{xl}{n}}

initfamily Test

end{document}

Sorry, but "MiKTeX Compiler Driver" did not succeed.
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!pdfTeX error: pdflatex (file Acorn): Font Acorn at 600 not found
 ==> Fatal error occurred, no output PDF file produced!