All ads and tracking can be blocked if you want them to. Its a arms race.

Disabling third-party cookies (desktop and mobile) is also easy to do. The only thing I’ve seen this break is inline support chat widgets. Enough clients have third-party cookies disabled (Safari defaults to disabled) that the chat widgets usually test for it and show an explicit message.

It’s much harder to block anything based on being logged in to a site (Google, Twitter, Facebook, etc), because:

* for retargeting based on intentional actions done while logged in (such as liking a YouTube channel): these can always get recorded, since the requests must succeed in order to complete the action you wanted.

* for conversion tracking: the hostname and even path of the conversion request can be very similar to that of an intentional request (like to login with SSO or to show content inline). The filter list entry is more brittle.

* for retargeting based on something done on a mobile device: you’ll need an ad blocker on the mobile device as well.

uBlock Origin with EasyList and EasyPrivacy gets as close as any other simple approach, though.

If you’re significantly more motivated, don’t browse while logged in to Google, Twitter, LinkedIn, or Facebook (and set their cookie duration short, like the current session). For most people, this is past the point of diminishing returns. If you change only 1, make it Google; it has the largest market share of advertisers, has the most services to target based on, and has the largest inventory.

Otherwise, put your money where your preferences are: move to FastMail or the like. Not because there’s anything wrong with Gmail (there’s not), or because they’re unethical (I have no reason to think they are), but because their product choices don’t meet your privacy preferences.

Hopefully anyone reading this far has already done it, but if not, pause everything on Google Activity Control: https://myaccount.google.com/activitycontrols