as ccgllc says, it's a bad idea to sell your coins automatically after mining.
Most miners chose to hold their coins for a set period of time or until the price has reached certain point, especially now that we are in Bear Trend and the price has risen a few hundreds dollar in the last few days.
But, no one restricts you from doing that, if you really need to automatically sell your coins you can set your exchange address as your mining pool withdraw address, and then turn on auto sell on exchange.
I don't know what exchange supports this option but I know that there are exchange with this option supported
They will sell your coins automatically the moment it reaches your exchange wallet to the current price available.