Planet.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class Planet : MonoBehaviour
{
    [SerializeField] List<Color> colors;
    [SerializeField] MeshRenderer meshRenderer;
    [SerializeField] Vector2 scaleRange;
    
    void Start()
    {
        meshRenderer.material.color = GetRandomColor();
        transform.localScale = Vector3.one * Random.Range(scaleRange.x, scaleRange.y);
    }

    // Update is called once per frame
    void Update()
    {
        
    }
    
    Color GetRandomColor()
    {
        return colors[Random.Range(0, colors.Count)];
    }
}