The only way to be sure is to look up the serial number against a 3rd party service.
You can check in the Apple Menu > About this Mac, however the model name can be misleading as some Macs haven’t been updated in many years. For example, if I were to purchase a new Mac mini today, the Mac model year would still say Mac mini (Late 2014) or a new Mac Pro would say Mac Pro (Late 2013) even though they are still current models.
My go-to source is Apple Serial Number Info - enter the serial number there and you’ll receive lots of information about your Mac, including an estimated build date (week and year of manufacture)