How increase back air suspencion on Cadillac DeVille?

To increase the rear air suspension on a Cadillac DeVille, you can adjust the air pressure in the air bags using an air compressor or an air pump specifically designed for vehicle suspension systems. Additionally, you may consider checking and replacing any worn-out components, such as air springs or sensors, to ensure optimal performance. Always consult the vehicle's manual or a professional mechanic for specific instructions tailored to your model year.