SystemInfo.maxGraphicsBufferSize

Description

The maximum size of a graphics buffer (GraphicsBuffer, ComputeBuffer, vertex/index buffer, etc.) in bytes (Read Only).

Any GPU buffer (GraphicsBuffer, ComputeBuffer or a vertex/index buffer used by a Mesh) can not be larger than this amount of bytes.

using UnityEngine;

public class ExampleScript : MonoBehaviour
{
    void Start()
    {
        // prints maximum graphics buffer size, in megabytes
        var maxSizeMb = SystemInfo.maxGraphicsBufferSize / 1024 / 1024;
        Debug.Log($"Maximum graphics buffer size is {maxSizeMb} MB");
    }
}