1996 Chevy Camaro Rear shocks or springs

Replacing the springs will generally fix that type of issue. However, I would look into a few otherr things as coil springs wearing out on a car is somewhat rare at that mileage and age.
First, shocks do not have anything to do with ride height or carrying any of the load of your car. Some vehicles will get or have a coilover strut which is different as the coil spring does seat on the shock.
But in your case the coil spring and the shock are 2 seperate things. Shocks only control the motion of the spring and prevent, "the Pogo" effect.
Since you are having issues and have shocks already, check them because bottoming out a new shock will blow the seal out and ruin the shock.
So, when you bottom out, are you carrying a large load or on a bad road?
Has the suspension been modified?
Are the rims and tires the stock size?
Also, bushings can wear out, but seldom cause a bottom out.
Let me know how it goes.

i have the same problem on a firebird 96 as well its your bumpstops its a common problem with them

If the bump stops are getting hit it is still bottoming out too far. The springs need replacement. A quick fix to get you by is a coil spring spacer. You can try to find one online and there is a site called, www.carrepairlinks.com that has a bunch of the best online retailers and custom shops that have hard to find parts. It is a good palce to start and if you order through links on site you get special discounts.