What is the process for applying for a retirement visa in Thailand with a French passport?

Best option is to apply for the Non Immigrant O-A visa before they make their way to Thailand. This visa is has multiple entry and is valid for 1 year. Each entry they would get 1 of of Admitted to Stay, so they can get almost 2 years of stay out of this visa. For travelling during the second year they need a re-entry permit.

Inside of thailand there is ONLY ONE option available to you for what's called a 'retirement visa'.

You first apply for a 90 day Non-Immigrant type O <-(O meaning other) visa based on being over 50 and meeting the financial requirements.

You apply and it goes under consideration for 14 days then you go back and get the 90 day Non-O stamped into your passport.

Then you wait until you have 30 days left on that stamp and you apply for a yearly extension of stay based on being over 50 and meeting the same financial requirements again.

These are the costs:

90 day Non-O visa 2000baht

Year extension 1900baht

re-entry permit 1000baht single entry, 3800baht multiple entry

I’m just in the car, but once home, I will look at Tods recently posted procedures

In principle the answer is YES

4 different Visa's and an Extension of Stay are all named retirement visa. Can you please explain us what you are looking for.