Does Lexus GS has Seat Features(Passenger)?

No, Lexus GS doesn't have Front/Rear Side Airbags.

No, Lexus GS isn't available in Seatbelt Reminder.

No, Lexus GS doesn't have Lane-keeping Alert.

Here are the width(mm) and variants of Lexus GS:

Here are the Sunshade and variants of Lexus GS:

Yes, Lexus GS has Head-up Display, which are: 2018 Lexus GS GS 300h.

Yes, Lexus GS is available in Parking Sensor Front. The available Parking Sensor Front variants are: 2018 Lexus GS GS 300 F Sport, 2018 Lexus GS GS 300 Luxury, 2018 Lexus GS GS 300 Premium, 2018 Lexus GS GS 300h, 2018 Lexus GS GS 350 F Sport, 2018 Lexus GS GS 350 Luxury.

Yes, Lexus GS has Immobilizer, which are: 2018 Lexus GS GS 300 F Sport, 2018 Lexus GS GS 300 Luxury, 2018 Lexus GS GS 300 Premium, 2018 Lexus GS GS 300h, 2018 Lexus GS GS 350 F Sport, 2018 Lexus GS GS 350 Luxury.

Here are the Driven Wheels and variants of Lexus GS:

Here are the Fuel Economy and variants of Lexus GS: