Screen.currentResolution

説明

現在の画面の解像度（読み取り専用）

Returns the current screen resolution (read only). If the player is running in windowed mode, this returns the current dimensions of the game window in pixels and the display refresh rate. If you are working with VR devices, use VRSettings.eyeTextureWidth and VRSettings.eyeTextureHeight instead.

using UnityEngine;

public class Example : MonoBehaviour
{
    void Start()
    {
        print(Screen.currentResolution);
    }
}