Stop loss on fno normal after market hours

Can I place stop loss on fno normal,after market hours?what will happen if a gap up or gap down is happening on the next trading day, whether that stop loss will work on the pre opening session?

For overnight positions, you can set stoploss using GTT orders. You can check out how to use GTT orders here. For better execution you can keep some difference between the Trigger and Price, so once the GTT is triggered the order will execute at the best available price in the market. However, it won’t execute if the price opens beyond the limit price specified and will remain pending.