Ah, The Lexus Paradox - people are drawn to the brand, in no little part, because of their legendary reliability, then spend thousands of pounds on warranties because they may not be reliable
It sort of depends, and on a few things.
I've only ever had low-value cars before, never spending more than £5,000, so warranties either weren't worth it or excluded. I was also physically able and knowledgeable enough to do almost any job on my cars myself, partly because they were less complicated then and had less electronics in them.
A couple of months ago we spent £25,000 on our new-to-us RX450h and it came with 12 months warranty, but we are very seriously considering buying another two years warranty, along with a service plan - partly because after a back injury I can no longer do my own work and partly because they are so complicated.
Only you can really decide if it's worth it to you.