The shaders were applied into the post-processing box so that the player can see the output.
Cel Shader
This gave the environment a flat appearance and made it look closer to being a 2D drawing that if I had left the normal lighting on.
I created a LUT so that the lighting had just 2 colours and the transition was a hard edge. This gives the shader the half-tone appearance.
Outline Shader
The outline shader didn't work and I had to download one from the Unreal Marketplace and combine it with my own.
You can find it here - https://www.unrealengine.com/marketplace/en-US/product/ce2cda95e5f54180b2cf7df24566bdf7