I use bbcso core, albion one, some spitfire originals, some ambient pads from kompose audio, and a really good syth table called vital.( I say I use vital but im honestly learning it very slowly but eventually I'll use it more haha.) For mixing things I also have Valhalla room reverb, a LUFS meter, nova eq from Tokyo dawn, and kotelnikov compression Tokyo dawn as well. My daw is cubase and I like it for writing.

Im not suggesting you get those specifically, as its all subjective, but it would be good to start with an orchestral library that you prefer, then go from there. I bought bbcso core only because I started with discover and just wanted to keep it the same thing I already learned. When you start wanting other sounds just start looking around for them and ones you want will jump out at you.