You can apply for non O retirement in Thailand from a tourist visa entry or visa exempt entry.
You require 800k baht in Thai bank account in your name only on day of application.
That gives a 90 day stamp.
In the last 30 days of permit, with money having been in the bank for 2 months you can apply for 12 month extension.
That plan is for retirement ongoing living in Thailand.
Is that your intention.