How to change array entries to a list's entries?

Given your short explanation it is hard to tell what you are asking but let's try anyways:

     List<GameObject> goList = List<GameObject>() { gameObject, someOtherGameObject, .......};
     GameObject[] arrayOfGameObjects = new GameObject[endIndex - startIndex];
    
     for(int i=startIndex;i< endIndex; i++)
               arrayOfGameObjects[i-startIndex] = goList[i];

this copies all entries from startIndex to endIndex from goList into the slots of the array "arrayOfGameObejcts".

if you just want to have the array form of the list use:

     var arrayOfGameObjects = goList.ToArray();

(i hope the latter one is not what you were searching for. If it is the case try to ask google first please)

If neither is what you are searching for write at least 5 sentences to destcribe your problem in detail.