using UnityEngine;

public class Test : MonoBehaviour
{
     void Start()
     {
         var sr = GetComponent<SpriteRenderer>();
         // Определяем точки в мировых координатах
         Bounds bounds = sr.bounds;
         float top = transform.position.y + bounds.extents.y;
         float right = transform.position.x + bounds.extents.x;
         float bottom = transform.position.y - bounds.extents.y;
         float left = transform.position.x - bounds.extents.x;
         // Размер в пикселях
         Vector3 size = Camera.main.WorldToScreenPoint(new Vector3(right, top, 0))
             - Camera.main.WorldToScreenPoint(new Vector3(left, bottom, 0));
         // Округляем до целых
         size.x = Mathf.Round(size.x); // Ширина
         size.y = Mathf.Round(size.y); // Высота
         Debug.Log(size);
     }
}