no, after your 90 O visa you apply for a retirement O visa in Thailand that is valid for 12 months. When the 12 months is up you then apply for an extension, you don't apply for an extension on your 90 day visa. It's pretty simple to understand, 12 month O retirement visas are issued in Thailand, and 12 month OA retirement visas are issued in your own country. FYI I have already done this.
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.