I just bought a 2019 1500 classic bighorn wanting to drop the rear 2 inches I will do some towing but nothing real heavy. My question is what's the best lowering springs for this application and do I need to specify that it's a classic when I order them thanks
Welcome to the forum, I can answer the order question with a yes you will want to specify it's a 2019 classic, or it may even be easier to just order most things for a 2018 instead. The 2019 classic is a 4th gen (2009-present) rather than the new resigned 5th gen that came out in 2019 as well. So for that reason, ordering for a 2018 eliminates the risk of getting a part for the new 5th gen.
I don't have a good answer to your other question as I do not have any experience lowering anything. I'm sure someone else will answer that though, if not here then you may want to try posting this over in the 4th gen lowered section, plenty of info and people over there that have lowered their rams.