% \setupmathfences[state=auto]

\setupmathfences[color=red]

\starttext
    \startformula
        \left( \sqrt{a + \sqrt{\frac{b}{c}} - d} \right)
        \left( \sqrt{a + \sqrt{\frac{b}{c}} - d} \right)
        \left. \sqrt{a + \sqrt{\frac{b}{c}} - d} \right.
        \Bigl( \sqrt{a + \sqrt{\frac{b}{c}} - d} \Bigr )
        \Big ( \sqrt{a + \sqrt{\frac{b}{c}} - d} \Big  )
        \Bigg( \sqrt{a + \sqrt{\frac{b}{c}} - d} \Bigg )
        \mathdelimiterstep1(
        \mathdelimiterstep2(
        \mathdelimiterstep3(
        \mathdelimiterstep4(
    \stopformula
\stoptext

