Simple Unity C# Script for using generated Atlas from Unity Sprite Atlas.

AtlasSpriteLoader.cs

using UnityEngine;
using UnityEngine.U2D;

public class AtlasSpriteLoader : MonoBehaviour {
    [SerializeField] private SpriteAtlas m_Atlas; 
    [SerializeField] private string m_SpriteName;
    
    void Start() {
        GetComponent<SpriteRenderer>().sprite = m_Atlas.GetSprite(m_SpriteName);
    }
}