How to access iPhone PUK code?

Your carrier can provide you with the PUK code to unlock / update the SIM card in your phone.

Call your carrier.

Perhaps if you've not tried to much, the iPhone may not be locked out, yet?

While I'm no expert, so far my iPhone just works; at least most ways, still.

Some ideas & the like, may be found online via search results, duckduckgo, etc.

•How to unlock the SIM card on your iPhone | iMore

https://www.imore.com/what-do-if-youve-locked-yourself-out-access-your-sim-card

This goes through ideas; arrives at P.U.K. codes, eventually. Says good & bad.

There are general search results, with other leads; they may be found here:

https://duckduckgo.com/?t=ffab&q=iphone+puk+code+access&ia=web

The related article above your post, mentions 'Personal.Unlocking.Key' barely.

• Use a SIM PIN for your iPhone or iPad - Apple Support

//support.apple.com/kb/HT201529