Microsoft in the latest versions of Windows 10 (21H1 and up I believe) are now hellbent in making sure you make a Microsoft account to use the OS. They got rid of the option to create a local account once it detects an internet connection.

The solution is simple. Do not connect to the internet! If you have a network cable plugged in, take it out. If you get the option to connect to WIFI, do not connect!
Connected to WIFI anyway? Windows will not forget and everytime you restart the process it will reconnect. Your only solution then is to disable the WIFI on your network untill you are done or move to an area with no internet with the laptop, whatever floats your boat.