Yes, you can convert USD to USDT or other coins to withdraw. To do this, you will need to sign up for an exchange that supports the conversion of USD to other coins. Once you have signed up, you will need to deposit funds into your account. After that, you will be able to select the currency you want to convert to and the amount of USD you want to convert. Once you have selected the currency, you can then place a buy order for the amount of USDT or other coins you want to withdraw. Once the order is filled, you will be able to withdraw your coins to a wallet of your choice.