@Stephen ******
As Brandon also explains, you have two options;
Apply for a regular Non O based in retirement. The requirements are income 65K baht or funds equal to 800K baht. You’ll need to bank 800K baht for your first year in Thailand. For your second year you can use twelve monthly transfer of min 65K baht a month.
Or
Apply for a Non O based on being married to a Thai. The requirements are income 40K baht a month or 400K baht. For the first year you’ll need to bank 400K baht in Thailand. For the second year they might accept monthly transfer of min 40K baht a month which not all immigrations do. Then you’ll need 400K baht every year.
So if you fulfill the requirement for a regular Non O and yearly extensions of stay based just on retirement, it’s the best and easiest route.