firebase - Restrict an array size up to N indices (Security Rules)

Question

Consider the following maximum array size:

Now let's say a user performs a push() childByAutoId. What I expect to happen is

if (arraySize > arraySizeLimit) {
// Delete first Index
}

I am fairly new to firebase security rules. I did some reading but still struggling with this. I apologise for not having any "attempt" code to present.

Answer 1

Waitting for answers