I got my 6T new, just the standard apps from OnePlus are on it and the Oxygen OS from OnePlus. With the Google account, I had all my data, settings and apps back in 10 minutes. Only the settings for the fingerprint etc. had to be set afterwards.

The phone is delivered new and in its original packaging.
OnePlus also provides you with a Fast Charge plug and a Fast Charge cable, as well as an adapter so that you can use the 3.5 mm jack (headphone connection).

You can quickly set up the phone with your Google account, otherwise there is also the OnePlus Switch app with which you can quickly transfer your data from the old phone to the new phone.

Great, thank you very much for the answers!