Find my date of purchases

If you're talking about the date of purchase of that iPhone, the only way to get the exact date is through your original receipt.

If it is a second hand device, you should ask the previous owner about that.

You can also check your warranty / AppleCare plan coverage, click here:--> Check Your Service and Support Coverage

If, on the contrary, you want to see dates of purchase of apps/subscriptions, see the section "Find information about older purchases" in this support article:--> View your purchase history for the App Store, iTunes Store, and other Apple media services

Regards

Giulio

If you want to see the date your iPhone was purchased, you must contact the place where it was purchased. If you want to see the day your iPhone was first activated, you can look up the phone's serial number here:

Start here:

Check Your Service and Support Coverage - Apple Support