With my 2018 Mini (purchased June 2020), I tried to buy AppleCare a few days after receiving but there was an issue with the site that claimed my AppleCard was declined. Ridiculous, because I had over $4000 of unused credit. Even more ridiculous, the AppleCare site didn't accept Apple Pay and I had to manually enter the MasterCard number. Have had no issues doing that on other sites without Apple Pay. I posted about this here at the time and others had similar problems.
So I was planning to try again with my Amex card, but forgot. When I checked, the site said I only had 60 days from puchase for the "no questions" AppleCare, and that had passed. So I just gave up, at least that saved me some money and the Mini has been absolutely perfect so far.