You need to create a custom location rule.
I did this a long time ago, but I do not think it will still work. It uses the old method of creating location rules and not the new method. Most of the code is probably okay but I think that the rule operators and rule values code would need to be updated, I have not tested it in a long time. https://github.com/Hube2/acf-filters-and-functions/blob/master/page-nth-level-location-rule.php
