Enable a ColourCorrection for only a certain player?

Honestly, I'm not entirely sure but we do know that BlurEffect, when used by the client, is local meaning that only a player can see it.

Then, that means we have to let the Player's Client create this effect. That means a remote event.

First, insert a RemoteEvent into ReplicatedStorage. Don't name it anything.

So first you have a part, and a script inside the part. First, let's use .Touched event

Now in the script:

script.Parent.Touched:Connect(function(h)
    if game.Players:GetPlayerFromCharacter(h) then
        game:GetService('ReplicatedStorage').RemoteEvent:FireClient(game.Players:GetPlayerFromCharacter(h))
    end
end)

Then, place a LocalScript inside of StarterPlayerScripts or StarterCharacterScripts

game:GetService('ReplicatedStorage').RemoteEvent.OnClientEvent:Connect(function()
    -- Clone or Create your blur
end)

This is your basic set up.

Hopefully, this helped.

Best of luck developer!