It definitely was possible in previous iOS versions and still is. Short answer is the last paragraph.
Be aware of Apple's big talk PR in interviews that is usually far from reality, for instance their speech about importance of users privacy, where they always forget to mention that Apple collaborate and make anti-privacy changes anywhere where they can make profit out of it (China, Russia).
Nevertheless, back to your question: you can at least check privacy page on apple.com, and you will see huge difference between what is commonly considered as valid and what Apple really declares:
Cit.: "Starting with iOS 14.5 and iPadOS 14.5, apps are required to ask your permission when they want to track you across apps and websites owned by other companies. You can change your preference for any app or prevent apps from asking for permission entirely in Settings."
To sum up: on iOS apps were and are able to track you across other apps, now with the newest version - if you can trust what Apple declares here - you can limit the ways apps can talk to each other.