AAA.cs

using UnityEngine;
using UnityEngine.Rendering;

public class AAA : MonoBehaviour
{
    [SerializeField] private Mesh _mesh;
    [SerializeField] private Material _material;
    private Matrix4x4[] _matrices;
    
    private void OnEnable()
    {
        var cam = Camera.main;
        _matrices = new Matrix4x4[900];
        UpdatePosition();

        var cb = new CommandBuffer();
        cb.DrawMeshInstanced(_mesh, 0, _material, 0, _matrices);
        
        cam.AddCommandBuffer(CameraEvent.AfterForwardOpaque, cb);
    }

    private void UpdatePosition()
    {
        for (var x = 0; x < 30; ++x)
        {
            for (var y = 0; y < 30; ++y)
            {
                var i = x * 30 + y;
                _matrices[i] = Matrix4x4.Translate(new Vector3(x * 1.5f, y * 1.5f, 0f));
            }
        }
    }
}