I routinely drive my Lucid AGT (rated at 512 miles, but realistically can only do about 380 miles, remaining SoC @5%) and my Rivian R1S large pack (rated at 300 miles, but I can do just about 310 miles using "Conserve" mode) on my 780 mile "commute" between Marin County and Arizona. Even if you have a TRUE 500+ mile range (and honestly, Lucid AGT does not), it wouldn't have made much of a difference because of fatigue and other biological limitations.
I am ASSUMING Lexus' 300-mile range is realizable at highway speed 70-75mph). If so, the Lexus SUV is more than capable for long range US Hwy trips!
I haven't seen any real-life test data on the Lexus SUV. Hence it remains to be proven. But I know that exaggerated claims of 500+mi range on some EVs are not realizable in actual US Hwy speed driving.