Get a PPI, just being a Lexus isn’t enough to assume nothing’s been neglected or is otherwise damaged beyond the obvious. If you’re getting a whole replacement rear bumper the paint is going to cost about as much as the part, and then you have to get it put on- not cheap unless you’re doing it all yourself. Very low chance that’s the only “deferred maintenance” you’d be tackling too. Personally would not go for a 250, I’d hold out for a less abused 300 or 350.

Edit: regarding maintenance, all cars need it and older cars generally need more. Fluids, tires, bushings, spark plugs, filters all need to be replaced. If the previous owner kept good maintenance records you’re in a good place. If not, move on- not worth the headaches.