How would one specify the font size in LMTX, but via x-height?
You could try this: \starttexdefinition setxheight [#1][#2] \switchtobodyfont[#1, 12pt] \switchtobodyfont[#1, \cldcontext{tex.sp"#2" / tex.sp"1ex" * tex.sp"1em" .. "sp"}] \stoptexdefinition Demo: \starttexdefinition setxheight [#1][#2] \switchtobodyfont[#1, 12pt] \switchtobodyfont[#1, \cldcontext{tex.sp"#2" / tex.sp"1ex" * tex.sp"1em" .. "sp"}] \stoptexdefinition \define[1]\sample{% \setxheight[#1][10pt] Hello% } \setuppapersize[letter, landscape] \starttext \dontleavehmode\rlap{\vrule width\textwidth height 10.5pt depth -10pt}% \processcommalist[modern, pagella, termes, heros, bonum, scholas, adventor, cursor, chorus, dejavu]\sample \stoptext This is kind of a hacky solution though. It works reasonably well, although there's likely a better (perhaps builtin?) way to do this. -- Max