I suspect that there may be many different warranties available. I bought my Porsche from a country wide BMW franchise, it came with a six months insurance based warranty having passed a BMW pre owned series of checks.... The warranty only covered up to a max of £4k for any one repair, which in Porsche terms equates to a degree of risk...?
I had my 991 subjected to a complimentary condition series of checks at my local Porsche centre who found that the alarm siren had issues... Circa £300 replacement cost... The warranty insurance paid for that.
After the obligatory 3 months had passed from the date of purchase my 991 was then subjected to and passed the 111 point Porsche checklist at my local Porsche dealership, my 991 was then eligible to join the Porsche extended warranty scheme which is again an insurance based scheme, which costs approximately £1k/annum and can be purchased up to a max of three years cover at any one time.
I guess there are warranties of all types some good and others perhaps not so good..?