there is a 90 day non-immigrant O visa, you get before the non-immigrant O retirement visa, which is valid for 1 year.
Generally in Thailand you get the 90 day O visa before you transfer to the yearly O retirement visa. You get the O retirement visa in Thailand.
Outside of Thailand you can straight up apply for a retirement OA visa which gives you a year.
If you use an agent or lawyer in Thailand to get an O retirement visa after arriving visa exemption, you will get a 15 month retirement visa, which is the 90 day O visa plus the 12 month O Retirement visa. It's a bit of a grey area to have them all at once, but you pay for the convenience.