Hi @ayrin,
To make realistic grass in realtime rendering isn’t easy, mostly due to the number of patches/strokes of grass you need to render.
Usually the billboard approach is what most games, even AAA games, use. If you can render a large number of them in big numbers then it can look quite realistic or at least sufficiently for the game realistic.
What I usually do, instead of forcing the grass planes to face the camera, I place them in random rotations, enable two-sided rendering on their material and use batching/instancing to draw a large number of them.
You can also add at the same time a wind animation (easily done so using a vertex shader) to make it look alive.
Here are some freely available grass assets to get you started: