A new laptop is usable out of the box, but an hour of setup on day one saves trouble later: updates, a backup, and removing the apps you will never open.
Do I need a Microsoft account to set up Windows 11? On Windows 11 Home, setup asks for one, and you need an internet connection to finish it. Windows 11 Pro gives more room to set up a local account instead.
Do I need to buy antivirus for a new laptop? No. Windows Security is built in and turned on by default, and it is enough for most people. Keep it updated and do not install a second antivirus on top of it.
How long does setting up a new laptop take? About an hour including Windows updates. The first round of updates on a new machine is usually the slow part.