Look up tutorials on YouTube. There are tonnes of them on grass.
If your grass is synthetic you won’t need much at all.
At a high level you need the model of the pattern of the grass, with that you generate a single line of geometry, you create a strip that contains the geometry and you bake the geometry to the strip to obtain the different textures.
You then generate a static mesh - for astroturf its quite low/pointless btw - and use the engine Grass output on the material to create a grass instance.
Theres exact tutorial on that procedure within the docs - procedural grass is what you want.
If your light is static and the color of the grass matches the color of the floor texture exactly you won’t have issues and can probably get by with less tris on screen for you would really struggle to notice blades of fake plastic grass further then 10m from the player…