How can my friend extend their visa exemption in Bangkok and apply for a COVID extension?

A US passport holder looking to extend their visa exemption while in Bangkok should go to the Muang Thong Thani Immigration office. The standard fee for any extension is 1900 Baht, regardless of the extension's duration. As for the COVID extension, they can inquire directly at the immigration office about its availability, duration, and any associated fees when they apply, ideally around January 4th or 5th.