I have no idea about collections, aside from the peripheral overview "everyone" knows. My game was built up incrementally over a nearly 3 year period, adding and removing mods one by one (ish). I suppose at one time that might have interested me. Now...not so much. (no offense to Nexus or anything. I can understand the desire for quickflood installs)
Also, like I sometimes suggest, nothing works better than plodding through the mod-categories section (in this case, targeting Environmental, Visual Graphics, Presets ENB and Reshade, Cities Towns...) . You can easily clear 40 or 50 pages of entries in under a half hour if you have some forehand knowledge of what you're looking for. just by scanning the link advert and the graphic they provide. And in addition, widenet searches (ie: "google it") with carefully chosen keywords can offer quite a few choice responses
ex: try "skyrim special edition spring summer green" and I suspect you'll find quite a few pertinent returns. (and having just "checked my math" I was right... well a few anyway) Oh, unless you're dealing with scripting issues or other debugs, always prepend "skyrim special edition" to your searches in order to filter out LE returns, which can (and at least in my case) can lead to accidental installs of incompatible mods.
FYI I'm using duckduckgo fwiw.