according thai law you ( or your landlord/ hotel ) must register you within 24 hours but immigration generally don't ask for it for 1st 30 days. I know many years ago, i needed a letter from my hotel to extend. In Phuket they don't ask for it. They ask for Covid extension however
There no COVID extension was refused on tourist or exemption on condition your address was registered in Phuket Untill further notice it will be like that till
COVID extension is a favour ( there are flights every day 😁 ) and depends on the officer but in general if you are registered and on tourist visa or exemption is always accepted
If this is first extension you don't have to be registered and can do in any immigration office For the law you have to be registered within 24 hours of arrival in Thailand however 😎
As far as i know, only Navakij ( from the companies accepted by Immigration ) accepts at the age of 77 But they end the contract at the age of 80 ... :-( This is a big problem for people, older then 70 or 75, who want to start a health insurance