I’m not 100% certain, but I believe you’ll need to log in with an MS account to be able to get to the main menu. Once you do that, it’ll prompt you for system updates and stuff that may take a while.

Other than that, offline support has gotten a bit better. You’ll need to configure a few settings, but once you do that you should be able to play most games without internet. https://support.xbox.com/en-US/help/hardware-network/connect-network/using-xbox-one-offline

Some games might require an immediate download, some may not. I don’t have a list unfortunately.