I don't remember any free games pre-installed and this is good news as you don't want anything imposed that you don't need or like. But take a look on the oculus store and you will find free games that you can choose to install and enjoy as soon as you get your headset. You can also brows the sidequest website from your quest browser and choose some free games from there too.
Hey, Sam! Welcome to the community! Great question. Like vrvbird said, there aren't any free games that come pre-installed on the headset, but there are quite a few free games + demos in the Oculus Store for the Quest and Quest 2 that you're more than free to give a try. I personally recommend Gun Raiders if you're looking for a PVP experience, or something like VRChat or Rec Room for a more social type of vibe. I've heard mixed things about sidequest, but haven't used it personally and it's worth noting that it's not supported by us. Might be worth using, might not, just do your due diligence.