\starttext

\startplacefigure
    \framed[width=.8\textwidth,framecolor=red]{one}
\stopplacefigure

\definefloat[widefigure][figure][figure]
\setupfloat   [widefigure][location=flushleft]
\setupcaptions[widefigure][width=\textwidth,align=middle]

\startplacewidefigure
    \framed[width=1.2\textwidth,framecolor=blue]{two}
\stopplacewidefigure

\stoptext
