I bought an S21 Plus from Ebay. I double checked with the seller to confirm that the phone was new / unopened. I received the phone today and checked the RTN. The reconditioned status said No but in the Life timer / call category, it had 8561 calls and 583H :58M. I had already used the Samsung Switch app to download settings from my old phone. Are the numbers in the RTN from my old phone or did I get a used phone?
www.gsmarena.com
You've bought a three year old phone from an Ebay retailer, is there actually that much of a price discrepancy between a dated 'new' phone or refurbished 'new' phone? Given that you've already restored your old phone user account to this new phone, presumably you recently went through the new phone setup process (i.e. adding in your Google account info, etc.) so do you recall what the initial prompt was the first time you started it up?
That might reveal if it was or wasn't a new phone, or if it was refurbished by Samsung or a third-party company. Did you need to remove things like the piece of plastic sticking to the display?
Since you've transferred your data onto it and been using it, be aware you need to differentiate any usage info you run across now as being tied to just your own previous phone usage, or might be the previous owner's phone usage data. But don't forget, the brand new or not status has yet to be determined.
Like the others, I'm also curious as to what you're referring to regarding 'RTN'? It's apparently a branded item, specific to particular carrier or manufacturer as it's not a typical Android reference nor part of common smartphone terminology.