\definepapersize[landscapePage][A4,landscape]
\starttext
\page
\adaptpapersize[landscapePage]
something.
\page
\startcolumns[n=3,blank=small,distance=2em,balance=yes]
\stopcolumns
some word, some word, some word, some word, some word, some word,
some word, some word, some word, some word, some word, some word,
\stoptext