In short
Ask for App Tracking Transparency (ATT) permission as a small favor. Users who do something for you start to see you as one of their own, and people buy more readily from their own group. Pick the right moment, explain that you need to know how users found you to help others, and offer a channel list or automatic detection.

🥸 Neuro-marketers have noticed that if you ask someone for a small favor, they're more likely to agree to a bigger request later.
And here’s why:
💡 Belonging to a group is literally a human need—only those who interacted within a group survived.
At the same time, we are:
👹 The most aggressive species
😇 The most empathetic—but only towards OUR OWN (pack, group).
If we do something for someone, they become a little bit of OUR OWN, and we are more likely to buy from those who belong to our group 🤓.
So, when you make a request for ATT:
3.1. Offer them a choice of channels from a list.
3.2. Suggest determining it automatically.
3.3. Combine both options.
🤓 You can make the "determine automatically" button easier to click
P.S. You won’t need to write tons of text in the system popup. Help users make the “right decision” 😇