My understanding is that the manufacturer's warranty has always been the same on Lexus vehicles: Basic warranty is 50,000 miles or 4 years, whichever comes first; drivetrain warrant is 70,000 miles or 6 years, whichever comes first.
My opinion is that automotive extended service warranties are rarely cost effective. I retired from an insurance company that sold them and where employees could buy them at cost. Few did unless they were buying a make or model with known issues -- mainly Chrysler products.
Service warranties are major money makers for automobile dealers and the insurance companies that underwrite them. Yes, some buyers of service warranties come out ahead but that is quite rare. If you "stretched" to buy your car, are financing its purchase, are sure that you are going to keep it at least as long as the term of an extended warranty, and cannot afford a "surprise" multi-thousand dollar repair then maybe an extended warranty is for you.