Can I extend my 90-day single entry tourist visa by going to the Myanmar border from Chiang Rai?

The user inquires about extending their 90-day single entry tourist visa as they approach the end of their 60-day period. They ask if they can extend their visa by traveling to the Myanmar border from Chiang Rai or if they must go to the immigration office in Chiang Mai. Comments clarify that extensions must be processed at an immigration office, with options available in both Chiang Rai and Chiang Mai, and that border checkpoints do not offer visa extensions.