Can an Australian extend their tourist visa in Thailand to 60 or 90 days?

An Australian traveling on a tourist visa can initially stay for 60 days, which might be extendable for an additional 30 days for a fee of ฿1900. If they have entered Thailand under the visa exemption rule, they also qualify for the 60-day stay with a possible 30-day extension. To extend, a visit to the local immigration office is required unless they're applying for the 30-day extension, which necessitates ensuring proper address registration (TM.30). The discussion also emphasizes checking the passport stamp for confirmation of stay duration.