Recent Android phones sync a ton of stuff automatically - which I suppose you agree to by signing in with a Google account, but that's also typically required. I know this because on the last two Android phones I purchased, a set of old outdated contacts from my Google account were automatically synced to the phone as soon as I logged in, which I was required to do to begin using the device.
Believe me, I would have opted out of this had I been prompted to do so during setup.