How can I get iPhone insurance when I don’t have any

Note that AppleCare+ as linked in the Related Article at the top left is not true insurance, it's an extended warranty with additional coverage. There's a limit to the coverage and like real insurance you have to pay what is essentially a deductible for each claim. You can only get Applecare within 60 days of purchasing your phone.

Check Your Service and Support Coverage - https://selfsolve.apple.com/agreementWarrantyDynamic.do - "Review your Apple warranty status and eligibility for support and extended coverage." Requires a hardware serial number.