Hi Kai, This is Ramesh.
Depending on the configuration, desktop computers can come with built-in Wi-Fi. Some OEMs offer the option of choosing the Wi-Fi card or buying without the built-in Wi-Fi. Regardless, you can buy an external USB Wi-Fi adapter if needed.
If you need clarification on a specific model, you may need to contact the seller of that product to get the detailed hardware specifications. Once you get that data, post the information here.