What will happen to my ETH on coin base when the merge happens?

Say I’m holding $1000 in ETH on coin base when the merge happens. What happens to my coins and their value? Will all my ETH automatically convert to the new ETH2? Will I get the same number of ETH2 or the same USD value in ETH2? Will I be able to sell at any point after the merge or is there a time period when they are locked even if I am not staking?