Can I purchase apple care plan after it expired

sahya97 wrote:

What if it already expired?

If it is less than 30 days after it expired you can extend it. Either if you made monthly payments or if you paid it in full. See→About continuing your AppleCare+ coverage for iPhone, iPad, and Apple Watch - Apple Support

Within 30 days of the end date of your coverage, go to Settings > General > About. Then tap AppleCare+ Coverage Available and follow the ...

Extend your AppleCare+ coverage

I don't think so.

What if it already expired?

No, if it’s expired it’s to late to extend it.

I also believe you can only extend it if you were making monthly payments.

Best bet is contact Apple support.