How do I extend apple care

If you purchased an AppleCare+ plan, it can be extended IF you live in a country where it is possible. If you are referring to the standard one year AppleCare plan which came with the phone, you had to have purchased an AppleCare+ plan within 60 days of purchase, and if you didn't you cannot extend it beyond the standard one year.

See this IF you purchased a valid AppleCare+ Plan for more details --> Extend your AppleCare+ coverage - Apple Support

Yes. See if this helps: Extend your AppleCare+ coverage - Apple Support