How do I disable monster level scaling?
Skyrim Scaling Stopper and Real Unleveled Skyrim both do away with scaling of actors (monsters, people etc) but in different ways.
SSS makes almost everything about the same level, with some very weak (especially near Whiterun) and very rare highly powerful spawns. The numbers of like this - 20% of spawns are level 1-14, 77% are level 15-20, 3% are level 21-50. So if you're level 1 you're going to get your arse handed to you most of the time; if you're level 50 you're going to breeze past most enemies.
RUS makes levelled spawns a lot more evenly spread out - some specific areas are fine at low levels; others shouldn't even be approached until much later in the game.
As for items, I think both those mods affect loot/enemy gear too. SSS spawns good stuff very rarely, and randomly; RUS has the best stuff in the most difficult places.
Morrowloot* is something that removes the scaling of items only, and well worth using (load it after one of the above mods). It makes items pretty much static & logical, so you'll only find dwemer items in dwemer ruins; orcish armour is only ever use by orcs; and so on.
Source: Reddit /r/skyrimmods comment by user Iogic in the post, "Are there any MODS that remove or reduce scaling?"
* There is a modified version of Morrowloot here: Morrowloot - N'wah Edition.
The overhaul mod Requiem as well as the Skyrim Redone module 'Encounter zones' do the exact thing you are looking for.