Erased content

An erased iPhone has no contents.

What to do before you sell, give away, or trade in your iPhone, iPad, or iPod touch - Apple Support

If you are unsure whether your passwords are still secret or have become known, change them:

If you think your Apple ID has been compromised - Apple Support

Also check your list of trusted devices (described in the first link above), the passwords to your email accounts (particularly those used to reset your Apple ID password), and enable two-factor authentication on your Apple ID if that’s not already enabled.

Did you do all these things before giving the phone away? If so it is very unlikely that they have access to your account.

What to do before you sell, give away, or trade in your iPhone, iPad, or iPod touch - Apple Support

If you are still worried check this link...

If you think your Apple ID has been compromised - Apple Support