How can I obtain a COVID-19 60-day extension visa in Chiang Mai without an embassy letter?

The post discusses the process of obtaining a COVID-19-related 60-day visa extension at the Chiang Mai immigration office without needing a letter from an embassy or consulate. The user shares their experience of filling out forms and paying a fee of 1,900 THB. They suggest that applying closer to the visa expiration may yield additional days, prompting questions in the comments about required paperwork and the location of the immigration office.