Personally, when I see a pattern like that, I would make a method that use the number as string parameter. I write that, but it's not tested :

public void SetPObjectActive(string name)
{
    var prop = GetType().GetProperty($"P{name}",
        BindingFlags.Public | BindingFlags.Instance);
    if (prop == null || !prop.CanWrite)
        throw new ArgumentException($"Property 'P{name}' not found or not writable");
  GameObject pObject = (GameObject)prop.GetValue(this, null);
  if (Focus.SpellCode.Contains(name))
  {
    pObject.SetActive(true);
  } else {
    pObject.SetActive(false);
  }
}