Unless you were to have captured a time screenshot of that battery's state of charge at the time you initially turned it on, I do not believe it is possible to retroactively demonstrate that it was delivered to you in that condition.
I do not believe you have reason for concern though. If your Mac's battery condition is normal, and it charges normally, and if you get an approximately normal amount of battery use after it has been charged to 100%, then I would not be concerned.
Read Check the condition of your Mac laptop's battery - Apple Support.
Some resellers may have their Macs in inventory for several months before they are sold. There is nothing you can do about that.