SpawnEnemy.cs

using UnityEngine;

public class EnemySpawner : MonoBehaviour
{
    public GameObject enemyPrefab;

    public Sprite[] eyesOptions;
    public Sprite[] noseOptions;
    public Sprite[] hairOptions;
    public Sprite[] pupilsOptions;

    private void Start()
    {
        SpawnEnemy();
    }

    private void SpawnEnemy()
    {
        Sprite eyes = eyesOptions[Random.Range(0, eyesOptions.Length)];
        Sprite nose = noseOptions[Random.Range(0, noseOptions.Length)];
        Sprite hair = hairOptions[Random.Range(0, hairOptions.Length)];
        Sprite pupils = pupilsOptions[Random.Range(0, pupilsOptions.Length)];

        GameObject enemy = Instantiate(enemyPrefab, transform.position, Quaternion.identity);

        enemy.transform.Find("Eyes").GetComponent<SpriteRenderer>().sprite = eyes;
        enemy.transform.Find("Nose").GetComponent<SpriteRenderer>().sprite = nose;
        enemy.transform.Find("Hair").GetComponent<SpriteRenderer>().sprite = hair;
        enemy.transform.Find("Pupils").GetComponent<SpriteRenderer>().sprite = pupils;
    }
}