Shaders are essentially nothing more but mods. So... you need a modloader, the mods and obviously a good resource and shaderpack to take advantage.

Now, fair disclaimer: all of the following is obviously based on my own personal preferences, there's more than what I'm showing you.

First stop: Prism; this is a so called (3rd party) launcher which can be used to fire up your game. Better yet: Prism can also make it a lot easier to install new Minecraft versions, apply modloaders and even download mods from both major websites (= CurseForge & Modrinth). I even wrote a guide about this some time ago.

Once you have that set up... install a new instance (I strongly suggest to focus on 1.20.1 for now because this version is currently best supported) and pick Fabric as the modloader.

Next stop: open up the mod section, select "Modrinth" as the source and go look for Iris & Sodium. Iris provides the actual shader support while Sodium helps to improve on general performance. It's a power combo. Remember: you don't need to use these links I shared, use Prism to grab these instead. My links are merely shared for reference.

But wait.. there's more! You see, if you install this stuff and fire up your game you'll notice that... wait.. nothing really changed?

You'll want to grab a resourcepack & a shader pack too! My personal favorite being CreatorPack (= resource pack) and Complementary Unbound; this shader has everything... moving foliage, awesome looking water (and sky), sporadic rainbows (my gf loves these) and best of all... (vanilla) ore blocks now "glow in the dark".

Lemme... just a moment... lessee.... there:



See what I mean?

(edit)

Meh, now I feel like showing off a bit more... so here's how it looks like on the surface:



Notice the shades (no pun intended)?

This is seriously a whole new way to play Minecraft, I can tell you that. Sure, my game is also fully modded but the shaders (and resource pack) definitely make it a whole new experience.

Hope this can help!