\usetypescriptfile[ebgaramond]
\usetypescriptfile[roboto]
\usebodyfont[roboto]
\setupbodyfont[roboto]

\setuphead[chapter]
[style={\switchtobodyfont[roboto,20pt]\ss}]

\starttext

     \startchapter[title=Whatever is the best title]
         \input tufte
     \stopchapter
\startchapter[title={Just a second title}]

Some random text.

\stopchapter

\stoptext