You can install Windows 10 without an internet connection. Furthermore, you will be able to use it as normal but without having access to features like automatic updates, the ability to browse the internet, or sending and receiving emails.

Does installing windows need Internet?

Installing Windows Updates requires an active internet connection to download the available updates onto your computer. If your computer isn’t connected to the internet it can not be updated.

Does installation require Internet?

Once your updates have been downloaded, it is not necessary. But if you want best out of windows 10, then it is good to have internet connection. The windows will start downloading updates as soon as you install it for which windows will require internet connection.