I want to be able to change the font and the font size inside a MPpage. But if I try to prepend \switchtobodyfont to the text inside textext it doesn't work. I'm using the following macro to set the font size via h-height:

\starttexdefinition setxheight [#1][#2]
    \switchtobodyfont[#1, 12pt]
    \scratchdimen=\dimexpr#2\relax
    \switchtobodyfont[#1, \cldcontext{tex.dimen.scratchdimen / tex.sp"1ex" * tex.sp"1em" .. "sp"}]
\stoptexdefinition

But I can't figure out how to use that in MPpage.

Any help would be appreciated.

Sincerely,

Stefan