I am a UK resident looking to visit Chiang Mai for just under three months. As I understand it I get visa-free entry to Thailand for up to 60 days, which can then be extended once for another 30 days, giving me a total of 90 days. Is this possible to do this without leaving the country? Do I need a visa agent to do the renewal?

Hey guys! I am Antonio, getting ready to leave the US Navy and move to Thailand. Can't wait to start my life. The military has been stressful. And knowing there is better ways to make money gets me excited. I always never understood why people work for people and do jobs they hate doing. Sailors complain all the time. But nobody makes a change. Life on a ship sucks bad. Low pay, gross environment and lower quality of life in general. I was kinda brain washed to join haha, the thought of going to Thailand making real money and being with someone I love, and in a cleaner environment, rather than being surrounded by negative people I literally resent. Gets me so excited. The plan is to leave within a 6-month period, after running a few errands and getting prepared to become a Digital Nomad in Thailand. Plan to make friends and mentors that can help me to get there. 😁😁 Very Respectfully, MA3 George