Why does my new iPhone 16 Pro Max show a cycle count of 39 and first use in December 2024?

We are all Apple-users, like yourself, in this community, so we have no access to your account-details or such.

Wondering where you bought the iPhone ...eg; could it be a discounted phone previously used for display.

You could check with the person or store you bought it from

or

If purchased online from Apple ... you could check with your invoice, your account, or Apple's "shopping help"

or

If purchased from any Apple store: You could try: Apple Support : There's a"Get Support" link {online chat / phone / email etc) at the bottom of their webpage.