I have a 1987 Cadillac Cimarron and I want to lower it but I have not been able to find any coilovers or lowering springs I have read 1st Gen and 2nd Gen Suspensions are interchangeable but that could be wrong. Any tips, tricks, and recommended products are welcome. Thanks!

Lowering spring sets used to be available, from at least 2 companies. I don't think they make them anymore though.
You might get lucky and find a used set for sale. Been years though since I've seen any. There is a facebook page J-body cars, but I've never been on it. If you use FB, might give it a try.

Tricks are to use these claps that bring two coils closer together. These will work on most springs. Not ideal of course, but I've seen them used many years ago.
https://www.oreillyauto.com/detail/c/superior/accessories/truck---towing/trailer---towing/trailer-accessories/spring-helpers---shock-extenders/b3ec48504439/superior-coil-spring-clamp/s pr0/181220a