Apps are self-contained. Even for ads delivered by Google AdMob, there is no ad-system component involved at all. Apps are loading ads and other data directly from the Internet.
Therefore, what you want is not possible. You can disable every app package by Google on your phone, but as long as the internet still works, the apps will show you ads.
The only system package that might be used is the WebView - a component that allows apps to display web pages - and ads are typically web content.
The problem is that many apps also use WebViews for displaying non-ad content, some apps even mainly consist of a WebView and the whole app consists of web pages.
The used WebView can be configured in Android developer options. On some devices, there is a separate WebView component installed, on others, the default web browser or an installed Chrome app is used as a WebView provider.
It is possible to develop an app that provides a WebView with an integrated ad-filter, but I have not heard of such an app.
It seems like there are already such apps available. Based on the information I found, Adblock Browser should provide a WebView implementation with integrated ad-blocking (not yet tested).
You have to install this app and make it the default WebView provider as shown in this answer.
However, using that app has one major disadvantage: it is based on Chromium, the open-source part of Google Chrome. Therefore, all vulnerabilities found in Chrome also apply to this web browser. So if you want to stay secure, every time a security update for Chrome is published (which happens some times multiple times a week) the developers of Adblock Browser need to update their project, incorporate all necessary changes, and also publish an update. Otherwise, apps that use WebView for regular (non-ad related) purposes may otherwise be vulnerable to an attack.
In the end, this is an advantage of ad-filtering external apps like Blokada or on the network level in your Wifi network, you can install a gateway like Pi-hole. Both filter apps and Pi-Hole work very similarly. You don't need to update them so often as security vulnerabilities are not so often found in such apps/systems.