The changes need to be made in your material instance.
At a glance. A tessellation multiplier of 1 won’t do much at all.
Also you aren’t showing us your material’s tessellation settings, so we have no idea if you configured your material properly.
Multiplying a texture by a scalar is not a “distance” in any way
if anything, that parameter is an intensity. You wouldn’t see the effect getting further, you’d see it getting taller.
multiplying the object radius makes 0 sense whatsoever on a landscape.
vertexnormal in world space is probably also useless, not 100% sure on that offhand.
Overall, tessellation (as of 4.23) may seem like a good idea, but it isn’t. Just enabling the setting you would have a drop in FPS of over 30 frames for no reason.
be it a bug, or just how it works, its unacceptable when you have an half decent looking scene.
hopefully, this is different in 4.24, but I have serious doubts seeing the state of all the other bugs currently in the released engine. If anything, it’s very probable that due to the layers they have made tessellation worse, or not touched it at all.
If you are still learning, you may want to consider alternative routes.
Meshes work much better with tessellation.
Also, because you are learning.
there is no reason at all to have tessellation at a distance above 10/20m.
if you do get a difference, you are using tessellation wrong.
You should develop a quick shader function to reduce the multiplier from a high value to a value of 0 based on distance from camera. A good filter to use for this is sphere mask.
Tessellation can help with adding Local detail on objects up-close without having to rely on different LODs.
Yet the same can be done with different LODs, it just takes time to create the mesh vs applying a texture.
It can also potentially help to smoothen out some rough/polygonal geometry, potentially, but let’s not go there.
My personal suggestion is to create meshes and paint them procedurally by using the Grass layer system.
You can quickly add a hundred or so flat, 10tris or so meshes around your view that are properly tessellated and actually add detail to the overall for a fraction of the cost of having tessellation enabled in the landscape material (again, at least as of 4.23).