Trading fees are always charged in the asset you receive. For example, if you buy ETH/USDT, the fee is paid in ETH. If you sell ETH/USDT, the fee is paid in USDT.
You place an order to buy 10 ETH for 3,452.55 USDT each:
Trading fee = 10 ETH * 0.2% = 0.02 ETH
Or you place an order to sell 10 ETH for 3,452.55 USDT each:
Trading fee = (10 ETH * 3,452.55 USDT) * 0.2% = 69.051 USDT
Learn more about fee rate.