Skyrim Special Edition's Community Shaders mod just hit 1.0 and became an essential graphical upgrade
If you're still playing Skyrim Special Edition and you haven't dived into the world of Community Shaders, now is the time. This is the toolkit you need for a vanilla-plus playthrough, with options that let you focus on the improvements you want while skipping the stuff that doesn't matter to you (and maybe saving yourself some frames). Now that it's arrived at version 1.0, there are even more reasons to give Community Shaders a try.
To get the most out of Community Shaders you'll want to install features like Water Effects, which adds depth to the surface of water and refracted light underneath, Grass Lighting, which makes all that planet matter pop, Subsurface Scattering, for more realistic skin, and Screen-Space Shadows, for more shadows on both faces and distant objects. For an example of the difference those can make, I've put together a little before-and-after slideshow below.
To install Community Shaders you'll first want to download Address Library for SKSE Plugins and SSE Engine Fixes if you haven't already, and then Community Shaders itself. The description page will link you to various features you'll want to add separately, though note that some of the older features have now been incorporated into the core mod as of version 1.0. If you have an older version you might need to delete mods like Dynamic Cubemaps and Sky Reflections Fix, which are now included by default.
As of version 1.0, Community Shaders now supports DLAA and Native FSR 3.1 AA, as well as frame generation. Also, PBR (physically based rendering), which has resulted in mods that retexture Whiterun and Riften, with doubtless more on the way. (Note that you'll need to run ParallaxGen after installing these so you can actually see the new meshes.)
While version 1.0 has clearly been a lot of work—just have a look at the size of those release notes—the Community Shaders Team isn't done yet. The list of upcoming features includes skylighting, Screen Space Global Illumination (SSGI), cloud shadows, HDR, water/SSR compositing, capsule shadows/AO, sharper textures when using AA, and a new weather/post-processing presets system.