Creating a target for bow&arrows game

I would go with a single cylinder collider and distance calculation from center point.

Following code NOT tested

 using UnityEngine;
  
 public class Target : MonoBehaviour
 {
     [System.Serializable]
     public struct Area
     {
         [Min(0)] public float DistanceFromCenter;
         [Min(0)] public int Points;
     }

     // Create an empty GameObject you place at the center of the target
     // The up direction of this empty must be perpendicular to the target surface
     [SerializeField] private Transform center;

     // Fill inspector
     // Order the elements from the smallest to the largest distance
     [SerializeField] private Area[] targetAreas;

     private void OnCollisionEnter(Collision collision)
     {
         Plane targetPlane = new Plane(center.up, center.position); // This may be created once in the Start method if the target does not move or rotate
         Vector3 contactPoint = targetPlane.ClosestPointOnPlane(collision.contacts[0].point); // Taking the 1st contact point may not be the perfect solution
         float distanceFromCenter = Vector3.Distance(contactPoint, center.position);

         for (int i = 0 ; i < targetAreas.Length ; i++)
         {
             if(distanceFromCenter < targetAreas[i].DistanceFromCenter)
             {
                 Debug.Log("The arrow reached the area giving " + targetAreas[i].Points + " points");
                 break;
             }
         }
     }

     // The code below is just to visualise in editor more easily
     private void OnDrawGizmosSelected()
     {
         if (center == null || targetAreas == null)
             return;

         for (int i = 0 ; i < targetAreas.Length ; i++)
         {
             DrawWireCircle(center.position, center.up, targetAreas[i].DistanceFromCenter, 8);
         }
     }

     private void DrawWireCircle(Vector3 center, Vector3 normal, float radius, int sides)
     {
         float deltaAngle = Mathf.PI * 2 / sides;
         Vector3 right = Vector3.Dot(normal, Vector3.up) >= 1
             ? Vector3.Cross(-Vector3.forward, normal).normalized
             : Vector3.Cross(normal, Vector3.up).normalized;
         Vector3 up = Vector3.Cross(right, normal);
         for (int i = 0 ; i < sides ; i++)
         {
             Vector3 from  = right * Mathf.Cos(i * deltaAngle) + up * Mathf.Sin(i * deltaAngle);
             Vector3 to    = right * Mathf.Cos((i + 1) * deltaAngle) + up * Mathf.Sin((i + 1) * deltaAngle);
             Gizmos.DrawLine(from * radius + center, to * radius + center);
         }
     }
 }